Transmissions... Transmissions...

[Step'67]

Hey, guys. Long time viewer, first time poster, so be gentle. Haha. I recently bought a '67 short stepside c10 and am in the process of freshening up the drivetrain. We (dad and I) just rebuilt the engine which is now a mild Vortec 350. (325-350 hp?) We are trying to decide on what transmission to follow it up with. As of right now it has the stock sm420 granny tranny. I like the durability of it, and the character it gives to the truck, but damn is it a pain sometimes, haha. My main interest of upgrading the trans is for the option of overdrive. I'm going to be finishing up high school here soon, then off to college. I plan to keep this old girl, and fix her up along the way. However, I'm going to be traveling on the freeway much more often, and overdrive would be a godsend. Not only that, but a much smoother, cleaner, and firmer transmission would liven up the truck. I haven't pulled the diff cover to see, but based on math the rear end is somewhere in the low 3's. (3.0-3.5:1) It's a slightly lowered 2wd, 26.5" outside tire diameter. I'd like your guy's opinions on what to do. Having a part time job, and in high school, i'm of course on a budget. I'm hoping to only spend a max of $2000-$3000 on this ENTIRE conversion, but all suggestions are welcome. Now the hard part, Auto vs Manual. I love the feel and control of a manual, plus it keeps you occupied, but from what I've seen, the conversion would be much more expensive. I'm looking right now in either a 700r4, t5/t56, or a TKO 500. Originally I was leaning towards the TKO, but budget wise I am being forced back to the r4. I've been trying looking at built up 700r4's online, but the reviews are so incredibly varied, I don't quite know what to do. Or, is it even worth the cost for the gas savings and driveability. My goal for this is a sport truck, fast and fun, but with the option of the very rare tow included. Again any suggestions would be awesome, thanks.