[yossarian19]

1.25 / 1.5" sounds right. Check siliconeintakes.com for silicone reducers, bends, etc - their tech guy said it's OK for coolant. Summit and Speedway sell silicone bends as well. Custom radiator hoses aren't as hard to build as you might think. You can use the summit online search to narrow down on OEM molded rubber hoses to cut up & use as well.

Radiator wise I re-cored mine & moved the filler necks. It was stupid expensive, but I can beat on my little 4.8 all day in any heat and the temp needle stays put.
Doing it again I'd buy an Ebay aluminum, put a Taurus / Volvo / Whatever OEM fan on it (or stick with mechanical) & build hoses to suit. Without road racing the thing I doubt you will overwhelm the radiator.