checking again on Britespark it looks like both those machines were also ATD jobs so no manual end caps
and yes whitakerpedia does have some data
http://www.voc.uk.com/net/docs/7.3/7.3-89-18.pdf but is from the halcyon days when you could buy a Lucas Part No. 458726-B3 off the shelf. I guess nowadays cost wise you would be half way to a BT-H , I think I will start with an ATD. Anyway its some way off I have just sent the head off to have a second 14mm plug hole added (For my decompression valve -though at 7.3 I may not need it)
The britespark part of it would not affect the mag', If you wanted to make it manual, You would have to grind a new slot in the cam, And finding the right place is tricky but not too bad.
Ron and me built a Comet for a Widow Friend, And in the BIG box of bits, It was never a complete bike !, Was a mag' that had been britesparked, When we came to set it up it did not work, We took it of and played on the bench and Ron had the drill going the wrong way !!, It worked !!, I said to Ron the cam is for anticlock, Turned out we think the mag' was for a Velo !.
I was 3 hours from my home at Ron's, I went there for a few days to get it going / finish it off,, We thought we were in the --it.
Lin emailed britespark and they rang us back, Very helpful !, I didn't think you could run an anticlock, Clockwise,
But they told us how and where to grind a new slot in the camring and to use a clockwise points, I think for some reason we didn't have the right points, So just to get it going we used the points going the wrong way.
Cheers Bill.