70 340 HP handling ability.

I think you could get close to 700 with boost if you build it right but if I was aiming for that power level with boost I'd be going Gen 3 Hemi or big block like a stroked 400... they have 5 head bolts per cylinder and a good percentage of those 400 blocks are unusually beefy. G3 5.7 blocks take quad-digit boosted power no problem.

But if you're planning a Ritter block build anyway I'd just save the nice internal engine parts for that build and put a TorqStorm on a mild-er ~400 hp setup with that 340 block for the time being, say to around 550 hp which is quite a bit safer. After all 340s aren't very common and are kind of valuable so it would be a bit of a loss if you happened to blow it up.