question about c10 axle with 4.10

[70chevrolet]

Hoping someone with more experience on this subject will chime in.
I recently built put together a 300hp sbc for my 1965 c-10 short bed. I installed it with a muncie M20 and my tire size is about 27" radius. I have a 12 bolt open diff with 4.10 gears that was original to the truck.
My problem is that the 4.10's are way too tall and 1st gear will tear your face off and 4th gear is good to about 50 mph. I want to swap to a set of 3.08's so I can enjoy this thing...(I defineately want 3.08 or close, I have considered 3.73, 3.55, 3.42, etc, etc) I didn't intend to build a tire shredder, I wanted a cruiser. Anyone know what years axles are interchangeable with these trucks and also if any other make and model gmc axles were interchangeable? I am thinking It would be more cost effective for me to just swap out a whole axle than to pay someone to re gear my axle. Because you know once I'm in there, I have to go with new bearings, gears, A sweet Eaton posi. not to mention the cost to set it all up.
I know chp makes kits to cut the brackets off a axle of similar length and fit them into this truck, but don't feel comfortable doing that welding myself.. I need a direct swapper.. I can swap axle shafts and/or brakes if need be.
Thanks in advace
70 €hevy