A freind pulled a 454 out of a motorhome to replace one in his pickup.
(kinda off topic I know but...)  He'd like any info anyone can give hime on
these engines.  Both the engines have heads that seem to be marked as "Hi
Perf".  Pics here:

http://cb.cliche-host.net/pics/454/454.html

the truck casting reads GM12T mfg 1975;  the RV; GM(I?)T mfg 1978

Both have 4 bolt main bottom ends.  Are these particularly rare or desirable
engines?  Would putting one in a farm truck be a waste?

Any help, hints, or comments wold be appreciated.

Thanks!