There are various ways to make the Vincent prop stands more efficient, and easier to use. You can even add a sidestand to the pillion footrest plate or sidecar bracket, which is marginally more convenient to extend.
Whatever you do, I would suggest that kick-starting the bike whilst on any stand, of any type, even the rear stand, is being very unkind to the stand, and inviting damage either to the stand or your person when the stand gives way.
They are simply not designed to take that strain.
Just saw my email response bounced so will respond here. Just spent a couple of days at the NA VOC parking on indifferent surfaces with these stands during rides with Micheal Breeding and they are superb to a fault ... for that mission. Though essentially unbreakable within reason, starting a machine on them , or any sidestand in general, leads to instability that rises with body weight and/or starting technique (less use of comp release).
It's sorta of a leverage thing here as I like to be able to park on unpaved surfaces which requires loading the foot as lightly as possible, which means more length while still keeping enough lean to impart stability. But, in this triangle, the variable is suspension compression during kickstart follow through. Vin's are very light machines, softly sprung, with a long kicker proving good leverage, a hearty thrust can almost bottom the rear suspension, standing them nearly vertical with risk of falling over to the right.
These stands can be bent/bosses ground such that a machine leans over sufficiently to offset right hand load, but I'd be more inclined to view my de-comp lever and flywheel inertia as the predominant tools for starting a machine than using the side stand as a back stop for this procedure.
These are the most elegant and stock appearing means to achieving a stable parking solution for your Vincent such that your rear stand/after market center stand will be relegated to machine servicing/storage rather than a primary (sometimes awkward) parking device.
If you do get a set of these stands, I'd forgo any bending of the arms (more on that below) to achieve your objectives regarding deployment or retraction, rather, remove some metal from the appropriate faces of the mounting castings where they abut your FT118. By virtue of casting stop radius to pivot relationship vs foot pad to pivot very little removal is required here to achieve major repositioning of said foot pads.
Besides the characteristics aforementioned when parked - light foot pad loading - an additional objective is some resistance to rolling of the stand when deployed. The farther you can position the foot pad forward of the 90 degree line of perpendicularity to the machine where the stand pivots when viewed overheard, the more you'll have a chance of decreasing this tendency because the radius of the pad to pivot decreases relative to that 90 degree line measurment requiring the machine to jack itself slightly when rolling forward in order to fall over. I add a slight measure of insurance and achieve more side ground clearance when retracted by welding my feet pads with their top face tilted towards the rear.
With installation on a B series this won't be as noticeable as on a C, let alone a C with longer springs, but, you will notice by virtue of their increased length they hang down a bit lower than the shorter originals. If you grind the stand bosses slightly you can achieve full retracted tuck against engine plates like stock and the reduced ground clearance shouldn't be an issue. I returned from 4 days of loading/unloading two machines from a Chevy cargo van multiple times daily on a standard aluminum ramp at the VOC NA rally without any grounding whatsoever.
I rode a Rapide in IoM in 1975, and it was exactly the same as my bike 30 years on. I remember parking in Ramsey facing "the wrong way" because when THE bicycle was in the gutter and the prop on the road surface, it was at a safe angle.
Skipping lightly forward, I had the casting machined to alter the angles, and an extension on the foot. It was just about acceptable if the bike was unladen, but mounting and dismounting when laden was fraught. It was about 50/50 whether I'd get off leaving the bike upright - if barely - or have to crawl out from under when it went over (slowly, as a great ocean liner might) when I was half-way off. (My wheels are standard 20" front, 19" rear.)
So I bought a Neal Videan stand, kept the originals in place lest i need to take the front wheel out on the road (at home i use a screw-jack) and life was thereby hugely improved. I don't doubt that machining the pivot casting, and or extending the leg has worked for some, but it didn't for me. (The fact that I don't straddle the bike with quite as much clearance as Peter is certainly a factor.)
The good news however is that if one decides to try, and I was glad I did, and it does NOT work out, there's a fall back option, and one is no worse off.