350 Crate Engine & more questions!

[1970CustomCamper]

First post.
I have a 70 GMC Custom Camper 3/4 ton with a 225 hp stock 350 engine and 350TH tranny. The truck has 69,000 original miles on it. Other than duel flowmaster exhaust it is stock. I bought it 6 months ago, and I love it. It is my daily driver and I work it pretty hard because I tow my work trailer behind it daily. The trailer is 1 ton dry and usually 2-3 tons full.
Problems- It runs hot. Has a clogged radiator. It leaks oil from everywhere. Has compressions of 140, 110, 90, 140, 120, 95, 130 and 140 in the cylinders. The plugs show corrosion (probably head gasket or cracked block). Factory AC doesn't work. Q-jet Carb needs to be rebuilt or thrown away.
Other than that it is great! LOL
I bought a whole bunch of goodies from Summit the other day with intentions of bolting them on to the existing engine. Gaskets, EDL valve covers, EDL intake manifold, EDL carb, EDL air cleaner, plugs, wires, dist. cap, aluminum radiator, water pump, 180 deg thermostat, water neck, timing chain and cover etc.
Now I'm debating a new crate 350 to bolt the goodies onto instead. I could buy a engine stand and build up a motor to drop in and replace the old.
1. 350 w/ 250 hp and 350 ft/lbs torque at 3600 RPM? -OR-
2. 350 w/ 290 hp and 326 ft/lbs torque at 3750 RPM?
3. Remove factory AC? Is this taboo? I don't really need it here.
4. Do I need to upgrade my transmission?
Price is an issue.
Advice is welcome. Help a brother out.
I'm in Southern Cal.
Dan