FWIW the above-mentioned '92 30' is going into E&B Racing in Lancaster, CA on Saturday for a "490# regular gas" rebuild. Ed is a long-time racer with a speed shop in front and a huge shop in back with a drive-on dyno that fits motorhomes. Guesstimate is around $5K all in. He's done dozens, if not 100's of RV motors (never mind the twin-turbo big block he ran in his SuperProduction car a while back.) He also installs Gear Vendors, etc.
I did all the homework on the crate tow 502, and what with injection chips, extra fuel pumps, weird brackets, iffy warranty, fussy installers, high test, dollars, etc., it seemed easier to give it to Ed. We'll see in 10 days.