Thanks for the quick replies.
The idea of using the JB Weld was simply to make sure the new profile of the lifter peg works. It does, but I don't intend to put the JB into actual service as I wouldn't trust it. The idea is to remove it & have the profile built up with welding. I take your points about expense & possible heat damage.
Fair question Ron.
I do have a new unit.But the valve seat's pocketed & the lifter peg strikes the tappet. As compression's good & the valve's in otherwise good condition it'll stay that way until the seat's replaced.
So the idea of using the old stuff was simply to avoid carving up the new one.
But it did all seem like a lot of work & expense, so since the parts are available I've taken a bit off the new unit to make it fit.
It'll hopefully be good enough when the seat's done, otherwise another will have to be bought.