225 slant 6

the block casting numbers, although ez to see are not the best way to trace back the pedigree of a slant six motor.
On an engine that had not had the combustion face of the deck milled, below the #1 sparkplug, kind of behind the alternator, there will be a series of letters and numbers stamped that will identify the day, month, year of engine assembly, the engine assembly plant, engine series.
There are online sites that will decode the stamping.
BYW, it is more than cast vs steel crank that will determine if your “turbo” slant six blows up. Read about the subject, attend a Slant Six drag race as a spectator, there you can talk face to face with folks that have actually put together a high performance slant six, get in the groove with the folks that know and I bet that you can build one to.