No problem. And pretty much where I was going too.
The rockers can be carefully looked at and compared with like dial indicator in hand to determine any differences without putting on a head. Of course the head assembly tells all.
Simply shortening the valvetips to clear lifter needs for the piddle valve can alter lift after a valvejob that lowers seats in head. You shorten for more.
Extreme rocker ratios can cause other issues other than VP clearance, depends on the setup, the tip can begin to push on retainer (explosive), the valve spring can load solid where cleared before (explosive again), the retainer can strike solid on the seal top, more lobe wear if loaded harder than factory intended (these are pretty hard though). Maybe even issues with the radius running out on the tappet end (unlikely). We see the outside of roller but what about bearing inside? They generally break with no warning at all until engine grenades from material going through head. Like V-8 roller rocker bearings, great until they give up the ghost.
If they move roller alone and all else stays the same the cam timing changes, roller will be advanced or retarded on lobe as compared to before and what got done. They may well re-index in the front timing pin to be able to still use exact same sprocket on front.
I wouldn't hesitate to surface head .040", that won't hurt anything, if you fire a gasket on that you were going to fire it pretty quick anyway. It may ping depending on your gas quality. Only raises compression maybe 1/2 point. Cut .100"? I'd be looking at chamber pressure issues like said, need bigger cam or retarded a bit to help out there. Cut head AND advance cam 6? Too much. a 8.5/engine makes maybe 170-190 psi compression squeeze, you can run WAY over that if you put it together right. No reason at all why an SOHC can't run 10/1 except for the gas quality alone, and using the exact same stock cam timings.
Swapping cams around a great idea if the parts work and so far I haven't seen why they don't, one just treads careful there. I'd be leery of heavy advancing of the cam with the head cut, throwing away top end power there and getting closer to any pressure problem. The extra lift with the short duration numbers could be just the thing for an ATX backed motor. These motors under certain conditions can get real b-tchy as far as driveability with just a little too much cam advance, the mid range gets funky and hard to carb correctly for it.
The end? Hey it's your stuff, do as you will. I used to look for oddball combinations like that at the shop all the time, we put 307 SBC pistons in 304 and 258 AMC jeeps and BBC rods in the 401s to better the L/R ratio. The engines were already a mishmash of parts from both GM and Ford right off the showroom floor, I had a Chrysler Hemi Torqueflite A727 in my 360 Hornet. Ford starter, GM distributor, coil, Ford carb, the list goes on.