gtex,
check chevyduty.com for the motor mounts. pretty sure they've got the ones for the 283. they've got good prices on lots of other stuff too.
as for the bellhousing, see 'em pretty regularly on ebay. there's alot to look at so you've got to nail down the key words when you're doing your search. could be wrong but, I think the 230-292's have the same bellhousing as the 8's which gives you a better shot at comin' up with something.
