There's is a bunch but cheap and easy ones to get are 4.8 and 5.3 which is 292 and 325
Same bore head cam intake just different stroke, with the right cam can get you in the high 400 hp easily, it's basically if 273/318 came with ported eddy heads stock, ford is all over head cam engines.
I have a couple of cars to check out and they are 318's. I thought that I would go with a 4 barrel, good true dual exhaust, curve kit, 3.55's or 3.73's. And possibly a mild cam and just enjoy the ride.
