OK I've been looking for a fix to my 91 rs 305, and ran across this add..270hp 305?..add states quote "a 2009 305 Volvo Penta Marine engine that cracked from not winterizing. It has 28 hours on the engine. None of the internals or heads are damaged. Engine ran fine, just the outside of the block was cracked. This engine was rated at 270hp from Volvo Penta. Its a vortec 305 gm engine. It would be great for parts or just put the rotation assm in another block."..could I use My 305 block and build a 305 that would work with my ECM?

GM makes the marine engines for Volvo/Mercury; its a genuine 305 GM with vortec heads on it.

If it has the intake with real fuel injectors it'd be worth grabbing even though it has a cast iron base for the intake. Besides that it's probably got something like the Ramjet cam in it too. Definitely a fairly decent set of parts there. If you had it set up as a roller block you'd probably want PROM tuning but yes it would work with some connector splicing.

Most of the marine SBC engines, esp the newer ones use the truck or LSx PCM which is worlds easier to tune than PROMs/chips

Id skip it and find a better base that isnt just a pile of parts

Your block may not be a roller setup? For the effort involved with that work your better off with some sort of 350 with similar parts that could give you even more power...

Ok thanks everyone for you advise..I will keep looking!