A critical measurement you need to do is the valve spring with valve fully closed.

36mm is the "fitted" length of the spring

If its too tight you need to machine the head to allow the spring to increase its length

I made a tool to do this exact job when I build Pinto engines

Kent Cams twin valve springs are uneven length but I do not use Pinto valve springs I use a pair of matched length valve springs and the tool I made allows the valve guide support to remain in place but the head around the guide is able to be machined

(Hope this makes sense)

Took 2 days on a spark eroder to make the tool









Yes I know it is an inaccurate "Coast Down" Rolling Road BUT as I always use the same rollers I am able to make usefull comparisons and it works for me !