honestly, if it needs sleeves, you should have just stuck it under a bench, and go pick up a magnum 318 from a junkyard, maybe rering/rebearing it, put a 4bbl intake on it, get the cam reground by bullet with their HR259/316 lobe, and use hughes 1110 valve springs with 2.2L retainers.

should be an honest 320-330 HP, and you'll most likely have less than $1200 into it including the price of the motor, it'll idle nice, run on 87 octane, and this combo basically pushes my 3900 lb 5th ave to low 14's while returning 17+ MPG in mixed driving.

to get that kind of power out of a 273, you're going to have a much wilder engine, and need to wring it out a lot higher.