How much horsepower should I expect?

I've made 530 with the 280R roller. But that was with more head and carb. I think for what you currently have, it will be fine. I think you'd do better with more more camshaft (230 at .050 is very small for the stroke, but the head are also a bottleneck), and a bit more carb. I run the Street Avenger 870VS on the 4" street engines with very good results in terms of power and mileage. Apples to apples that would be a 950+ cfm Edelbrock...lol. The smaller carb will work, but I think it's a little mismatch there. As built, it's fine, but there's a lot more in that shortblock for changes later.