Gear vendors would be awesome, with some extra gears, and lower rpm on the highway. Keeps the 4.10 like it was supposed to be. Just need to figure out how much money to put into it. I have had the car for about 4 years, and I think I'm in it pretty good, $$ wise. GV should add some value. Looks like these cars currently have pretty good values. Not too sure of the value of mine, but not ready to sell yet, anyway.
Right now leaning towards Gearvendors. Thanks biomedtechguy!!
All of that...
I watch EVERY Mecum auction, focus mainly on the 60s and early 70s cars, especially Mopars. "Clones" or "Tribute" cars are bringing good money depending on how desirable the version of "clone" is.
For example, my wife's GTO is a real 65 GTO, but it started as a PHS documented 4bbl 389 and it has a 421 Tripower in it. Date code October 65. I did intensive research into Royal Bobcat upgrades, and for the sake of brevity, here's the connection.
My dad won 1st place (still has the trophy) at LaPlace Dragway in 65 with his 65 Tripower 389 4 speed GTO, racing another 65 GTO, and he had the "mail order" Royal Bobcat kit in his car. Running "stock" class. That was the 1st step of 3 levels available for the 65 GTO from Royal Pontiac. The top level was pulling the 389 and dropping in a 421. Because of the date code of the 421 we have, the Royal Bobcat Tribute description is perfect! So that adds value to an already valuable car, other than for a buyer looking for factory correct, but that leads me to your car, my car, and the GTO we have...
By emulating a step up, highly desirable package, in your case the A-12, you can have some fun on the street and at the track, get a feel for what the real thing performed like (they are legendary for a reason) but not have to worry about chasing all correct, NOS, yada yada or worry about hurting something irreplaceable, putting too many miles on it, or making some changes, preferably reversible, to enhance the performance or make it more like you want.
Along those lines and harkening back to Mecum auctions, pro touring or resto mod changes, when done right, can actually bring a return value beyond what an original factory correct restoration would bring.
In my case the Passon 5 speed makes my car WAY WAY better to drive on the highway, and also gives me confidence that it isn't going to explode behind my current motor or my future stroker motor.
In the case of the GTO, we have a TKO600 going in, we put a Quick Performance Ford based 9" rear axle in and upgraded the suspension and brakes. So it's faster, stronger, more pleasant to drive, a blast at the track, and turns heads on the street. I put a 3.80 ring and pinion gearset in the GTO because I wasn't sure if my wife would want an aftermarket 5 speed, and the 3.80 was bearable on the highway, and with the 8 3/4 or 9" pumpkin style rear axle if we decided to road trip the chunk could be easily swapped out for a more highway friendly ratio. Now that the .60 5 speed is going in, the 3.80 stays (because the bore and stroke of a 421 doesn't rev as high as a 440) we still enjoy better off the line performance, but the 5th gear makes everything great!
So either go Gear Vendors and keep the 4.10s and have the best of EVERYTHING, or get a 3.23 and swap that in for long road trips, and then swap the 4.10 in for spans of time where that is the ride you want. The swapping is doable, but the Gear Vendors gives you EVERYTHING, and the investment is worth it with what you have in an A-12 Tribute car.