Matt what is the purpose/use of the car ?
Just in city/local driving
Long Hwy Trips ??
I am not fan of 700R4s
so that being said and based on your answers to the two above questions
I would go either a TH400 3 speed Auto Trany, which is pretty much Bullet Proof
go with a 4L80M 4 speed Auto Trany, which means you do not need a Expensive Electronic Controler
and is pretty much Bullet Proof since it is basically a TH400 with a Overdrive
And if you have not done any Suspension Parts buying yet
after much Researching I bought these UMI Perf parts for my 67
and found them to be of the Best Quality / Fit and Finish of any of the Aftermarket parts out there IMHO
I looked at various other companies
eg. BMR Fab. / Hotchkis / Edelbrock / Hellwigs / SC & C / HRPartsNStuff / Speed Tech .....
I would have purchased the UMI Perf 64-67 GM A Body Handling Package- Stage 2 # ABF403-64
except that the kit came with 1" lowering springs
which I did not want or need as I run OEM stock Moog springs for the stock riding height.
I purchased the following from UMI Perf and found them to be
of the best looking & quality that I have ever seen/used;
1. UMI Perf 64-67 GM A Body Rear Lower Boxed / Adj Upper Control Arms # 402126
2. UMI Perf 64-72 GM A Body Solid Front and Rear Sway Bar Kit # 403534
3. UMI Perf 64-72 GM A-Body Tubular Upper & Lower Front A-Arm Kit # 403133
4. UMI Perf 64-72 GM A-Body Tie Rod Adjusters # 2103
5. UMI Perf 64-67 GM A-Body Rear Shock Tower Brace # 4059
Also I added the Rear Frame Cross Brackets.
The difference in ride quality/handling , went to firm and stable,
that I have acquired with the great parts from UMI Perf I put on from the previous original type Springs
it was a night to day type change in ride and handling response .
See the various Kits for your car here
Handling Kits : UMI Performance, Inc.