Hot Rods What Overdrive and Cylnder Head To Use With Model A Engine

The headline says it all. I am going to build a Model A engine powered car and have been researching the overdrive units available. I'll use a '39 Ford style gearbox mated to the A and I see I may have many options for the overdrive,from a brand new unit for over
$3,000 to other options.
I'm guessing a few on the forum have run overdrives on their A engines so would like to have some suggestions. I know the early 50's Fords used overdrives and had side shift
transmissions and wonder if one of those could be adapted.
The after market OD's can be ordered wit 23% or 36%, and the latter is not recommended unless you have a very strong engine.
Which brings me to my engine. I'd love to have one of the Miller heads that cost over
$7,000 and will run $10K by the time you're done.
So do any of you have experience with just a high compression head? You can see I
am buying myself an education with an engine I've been familiar with for decades, but
never considered using one.
My mission is learning the craft of coach-building, i.e. building an entire car body.
I want to use the 1935 MG Airline coupe as my basic design and upscale it to nearly Model
A Ford specs. For example, the MG has an 87" Wheelbase, the A is 103"; track on the MG is
42", the A is 56". So my plan is to carve a quarter scale car in Chavant clay, which will take a few hundred hours, and then turn the model into reality. The MG has a frame that goes under the rear end, something I hadn't seen before. So imagine the Airline Coupe a few inches longer, a little wider, and powered with a Hot Rod Model A engine.

 

my avatar has a 7:1 Lion Speed Head and the 84-87 F150 3 speed with overdrive.