68 cuda automatic to manual conversion

I have a notchback 68 with a SM 408 stroker, mild cam and I want to install a manual trans
I reached out to Brewers and they can sell me the linkage/pedals but they will have no 833s for at least 1 year , waiting list . Silver Sport transmissions sent me an Email saying that the cost would be well over $8k for parts and too much work , definitely not a hard sell
Can someone recommend a good thread and different combo solutions .I have budgeted 5k for the conversion . Tremec t5 or the A500 ?