Gear, Torque Converter, & Drivability

[cm113]

I have recently traded for a 68 c-10 that at some point was intended to be a drag truck I assume. The guy I got it from had big intentions and ran out of money after he put the cab on the frame. I intend to make it into a sort of street legal ride that will only be driven to the local cruise ins and small shows plus just to drive around on occasion.
It has a 383 stroker, vortex heads, Edlebrock TRI intake with 2 450cfm Holley carbs, Mallory ingition with rev limiter box and an extemely hot cam. Behind it is a TH400 with a TCI Street fighter stall (3500 rpm i think). All this feeds a Ford 9" with a spool and 5.14 gears with 31x18.50 Hoosier tires. It has been converted to leaf springs with some sort of traction bar/wheel bar set up. It has never really been drove or ran other than around the parking lots. Have been working out the bugs since I have gotten it. Carbs had never even been adjusted. Anyway,

I figure I will probably change the gears to a 4.10 or so to get some highway manners, but not sure how this converter will act once I do? Would like some opionions before i fork out the money for new gears. The way it is set up now, it will set it back on the wheelie bar on a good launch. But the engine is really screaming when you try to run down the road at anywhere near highway speed.

Just looking for some input on what gears would be good, and what converter would work if I need to change it.

Thanks for any information.
cm