I've always favored the H23a1 for a swap, though I wouldn't be so quick to up your numbers.
With the longer stroke of the H23 you'll make more torque, but your power band is lower than the H22, meaning you won't be zinging as high for peak HP numbers. Less HP, better power band. It's a tradeoff I'd be willing to make myself. Of course you can always build an engine to make power higher up with enough money, but there are compromises with that as well.
Anyway, Roscoe will be your new best friend
Rosko Racing, and you'll need every bit of his help if you want to get 270 out of that motor. He has several build threads on H-T you can check out, but I don't recall him making those kinds of numbers, even with his infinite collection of custom parts he can produce. I think his latest venture was going to a B-series trans in his Prelude IIRC.