possibility of honing it
The venturi can be enlarged slightly by hand if you have a good eye. The minimum point is increased by 1/16" or so, and the cut re-tapered back into the shape above and below. If they use a go/no-go gauge for venturi size, they'll catch you. If they just do a visual and check the throttle size and part number you may get away with it.
Stock air cleaner, meaning the exterior can? Add a velo stack inside aligned to the air-horn. Do you have to use the stock element, or the stock size element? If the exterior can't have any attachment, make a heat shield to mask it from hot air off the manifold.
"Illegal camshaft" was almost universally used, based on the only test was the base circle and the lift (to catch re-grinds). A whole new shape can be used with those same figures, even with the stock timing figures - all it takes is money.
There were no good piston at the time, and saving weight on the original is not something I feel confident in doing.
For quench, you may have to make a gasket because quench is absolutely necessary.
In my opinion, removing metal from an original part was generally OK (as opposed to replacing it), but whether they do anything about it doesn't entirely depend on the actual rules (sorry, my own experience). The "gray area" is your personal relationship with the tech people. If you win, and the other guy is the sponsor's brother-in-law, you're toast. If he wins, and you protest, they won't listen.
The ideal deck thickness is stock, the question is how much will wreck the gasket seal. IMHO -.040" is fine, use studs instead of bolts.
I wouldn't try to lighten the rods at all - they're really small on the pin end where it matter.
Depending on your seat condition, a deck cut may remove part of the seat. Don't re-cut it any deeper than you have to, to get the same width as the valve head. The valve seats should join the chamber similar to a Ford V8, except the Ford has "tilted" stems.
The head's open (non-quench) area can generally be improved, but this means filling with brass or weld. Volume can be reduced by milling (but doesn't change the quench clearance unless you have positive deck pistons). The pocket behind the valve can be filled in and re-contoured to a better shape.
Have you got pictures of the deck surface and chambers?
