if your going to log miles...3m front is a yes! mine was install at custom cars, very well done.
mirrors, I don't like my ray-dot or the way BRD mounts them... but still don't have a better option. I do have one of the clip on convex dash mirrors...it works good.
steering wheel...up-grade! Jay should have some good options. on the short shifter...I think this is a personal preference thing, I built my own flat hurst style forward shortie...i like it!
just installed the billett knob...sweet!
solid mounts....just installed with the 347 stroker...you feel more engine vibrations...have not driven many miles to form an opinion yet, if impression, don't know if I like it, but a very simple change if you don't. (at least on a 302 base motor)
391 gears...that's what i have and it good. you'll be better with the higher RPM's of the new 5.0! what the first gear ratio of the t56? hopefully not in the 3's?
one item not listed...rear shock...i'd get KYB's...not sure if they are still shipping car with Gabrial's...to soft, bilstiens to hard, KYB just right....but this is me.
btw...sounds like a nice build! Jay's a good guy to deal with also!
I've logged 14k mile on my car on 5'ish mo/yr of driving, you'll love it.
my 0.02!