Small update. I need a transmission so I can mock up the engine/trans to make mounts and to make sure that I leave room around the drivetrain when building the X member. I thought about a T5 from an S10 but I don't think those will be strong enough once I get the 250 built. I don't want an auto because I'd rather stir my own gears, and because real hot rods have three pedals.
I did some searching and found that a T56 six speed is rated at around 400-450 ft/lb and used ones aren't extremely expensive so I'll go with one of those. Should be able to run 4.56 or higher (numerically) gears to have fun around town and still be able to cruise comfortably at 80-90 mph since 6th gear is .50 to 1.00 ratio. A local shop that sends us all of their glass work has one and said I could borrow it to get the X member and engine/trans mounts built. I'll probably just go ahead and buy it from them after Christmas/New Year's since he's not wanting an arm and a leg for it. It'll get converted to mid shift so the shifter comes out ahead of the seat. Once I get the frame boxed and ready for engine mounts, I'm thinking about sitting the cab back on the frame to check for floor/firewall clearance and to see how far down and back I can move the engine for better weight distribution. We get a week off between Christmas and New Year's so I'm hoping to be able to get the frame boxed and engine/trans mounts made while we're off and the shop is empty.
Dad had a steel table frame that needed to be powdercoated so I went ahead and took the bed floor support channels and a few small peices with his table frame to the powercoaters, and they'll be ready to pick up this week.
I've also decided to move the gas tank to behind the axle for better weight distribution, and may move the battery also. A trailer hitch will add some weight in the rear too.
Hopefully I'll be able to make more progress soon, just been too busy lately to get anything done.