Like Wayne says, how has it been sitting and how (and where) has it been stored? That would be my biggest concern.
It should be good, by my wild-assed guess, for about 260hp if it was running correctly (you don't say what the compression ratio is, but I assume 9.5:1 or less for single plug). As part of my upgrades (quite similar to what you describe) I was told that the magnesium cased, 7:31 ring and pinion (if it is a '74) won't last too long if you drive in anger (on the track). Then again, you might be alright.
Mahle do make 98mm P&Cs to fit an SC wrist pin.
ANDIAL has them in CIS and carb/MFI specification (difference is dome shape and valve recess, I think - the carb/MFI ones will take up to RSR cams). About $3k a set - ouch - ask me how I know.
In good condition, I personally think it is worth $10k. It would certainly cost more to build...