How much can valve head OD be cut?

LOL, I'll stick to the mid-300's for now. 335 ci as it stands at this moment.
Status:

• Pistons found to work off the shelf; cast or hyper options, but not HP hypers, so I am not going to push things hard at first
• Crank, rods, and pistons mocked up to check piston-crank clearance; all good with no machining except for some very small bore botches at the bottom
• Pin bushing problem worked over to put pistons on standard Mopar rod lengths and a solution found
• Bobweight computed, and as of now, is in the low 1600 gram range with SCAT I beams (nice!), meaning that the 4" stoker crank should be balanced by some simple weight removal, no heavy metal
• Piston valve clearance looks good on a detailed simulation spreadsheet with a .520" actual lift at the valve. The piston heads will probably need a touch-up with the Dremel in a spot or 2 once mocked up and P-V clearance checked.

So this matter of cylinder bore notching for the intake valves, and not running into the top of the ring travel is the last step in the process. I can back off and use iron Magnum type heads with 1.92" valves and be better off. (Or I just may back off the lift some, but this is a cam I wanted to try.) I prefer AL heads, but just cannot see how to do smaller valved ones with all the 2.02" valved products out there.

A teaser pix of a piston at TDC; deck height ended up at about -.017" with with no decking done yet: