Going from unported 2.19 intakes to fully ported 2.25 intakes will increase flow at the higher lifts from about 310 to 380 cfm. With the right shortblock of 528 or bigger with a 4.50 bore and all the whistles and bells you are looking at as much as 150 to 175 hp. If you put them on a small motor with a flat tappet cam, you will get much much less.
I went from a 499 13/1 on alky with bowl ported -1s running 2.25 intakes to a full on port and polish, 528 big bore megablock and picked up from 9.30s to 8.80s at 3,000 lbs. I also added a vacuum pump and better pistons with .043 rings and gas ports but that was about the extent of extras besides the head work.