all poncho's use the same basic casting. the size of the water jackets varies from year to year and there are huge variations in how good/bad the metals used in the castings were. the larger motors were actually made better, delorean had no respect for 326/350 motors as he considered them only service pieces and a 389 and larger motor he viewed as performance pieces.
why keep a poncho? low end power. pontiac motors don't spin to 6500 like a lot of motors cause of bottom end oiling issues, but they don't really have to either. ponchos make a ton of power right off idle thanks to far better head design than anything chevy ever put out.
poncho motors also sound a lot different from anything else, they start sounding mean with a stock cam and it only gets better the more cam you put in it
