you hit on something very important here: breaking even isn't the same as making money!
as an exercise say, 3K price point on a 340 block you'd have to sell 100 to break even at your initial 300K investment. and what's the ROI time wise? 18mo? two years? there's better, faster money to be made with that coin. (granted 2nd run with amortized costs and built in process, but still... you clear what? 1500 on a block? so now you have to sell another 100 to bank 50%)
then, you have as
@AndyF noted, if you're gonna do it why not go ahead and make it
better? well, then you're in the boat of needing proprietary or specialty bits. which, that's cool if you
also produce those and are seeing some dough there but a huge bummer for the guy looking to buy a repop 340 block and transfer all his stuff over and not have to drop 1500 at the machine shop and 2K for a cam & lifters.
it's a great idea, but it's 100% about volume and there's just not enough there.
if the angle already existed, MP would've covered it, made it and then backed us into the corner, knife out and demanded our wallets.
which, granted, many would've gladly opened up and let them go elbow deep in the calf skin. but that's the 1% of the 1% of dudes that are all: "i'd totally buy a 340 block if they made 'em".
and that brings us to the age old truism of: cash talks and bullshit walks.