1989-91 360 roller cam engine questions

My son picked up a factory 360 LA roller cam engine. We're doing a full rebuild, swapping to a carb and putting it in an older W150 truck. He's planning on running a CompCams 210/220 Hyd Roller ram with the stock roller lifters (good shape and we have a budget) The truck is lifted on 35" tires, 4 speed manual (no OD) and has 4.56 gears. (A bit low for this swap but he was rocking a slant six before!) So this cam is good for 900-5200rpm which is about right and has advertised duration of 264/274 and lift of .48 with 1.5:1 rockers. 112 lobe seperation.
Now this question. I know these 308 heads use valve rotators on the exhaust valves and need to swap the springs and retainers. I think the valve spring seats need to be cut down as well to get the proper installed height. I think the stock exhaust valves have the lock groove further down on the stem than most 1.60 valves. Is this right? If so, can we swap to a standard exhaust valve and probably not have to cut the seats? This would also give more room for the valve stem seals.
Planning to run the SpeedPro H405CP30 hypereutectic pistons with moly rings. These are flat tops with valve reliefs, which if all my math is close should be a 9.0:1 CR, or there abouts.
So, aside from the valve question, do you think this cam, pistons selection, a Holley 650 carb and a dual plane manifold will yield a 320-350 HP motor?
Oh one more thing, The timing cover has half the provisions for a mech. fuel pump. The right bolt hole is there, but has a raised boss on it. The left hole does not exist and the hole for the arm is just a recess (not a hole) I plan to machine it open, remove the raised boss and drill and tap the missing hole. I assume this location is correct and that Chrysler just stop machining them all the way so they wouldn't have to use a plate.
Be easy on me, I'm an ex diesel guy...we just had to shove more air and fuel at a stock engine, LOL
Jerry