I feel your pain mfhutchins, When I got my '61 Super Rocket I sent the motor to SRM for numerous improvements and after assembling the bike very carefully, after 500 miles I noticed a knock in the top end, turned out to be a spun little end bearing, done by SRM, they fixed the rod after I removed it and sent it to them, after reassembly one again the performance went bad after another 500 miles, turned out to be SRM's 357 cam had worn flat, "we had a bad batch, send it back to us and we'll replace it"....another dissassembly and reassembly. After 11,000 miles SRM's special timing side conversion bearing went bad, I sent it back well out of warranty with a curt note saying I had expected this bearing to last longer than 11 K, and they sent me a new bearing, and yes one more dissassemble and reassemble. All this wouldn't be too bad if I lived in Aberystwyth Wales, I live in California USA. All that being said I have gotten quite adept at tearing down and reassembling A10 motors.
Bottom line is you probably should start by compression testing, then removing the rockerbox, make sure there are no broken valve springs etc, if all looks good then remove the head and finally the barrels, you could do it in an afternoon, and in my opinion it's worth it for the peace of mind. I know full well the P'd off feeling you have, have a pint, put on your favourite tunes and go for it.
Good luck mate
Clive