Auto to manual conversion. If you could do it over....regrets, pitfalls, long term opinions???

I debated the t56 6 speed viper trans and the passon 4 speed hemi overdrive.
I went passon and cruise with my Hurst ram rod and 4.30 gears. Overdrive acts like 3.55 gears and I cruise around 2700 rpm.

The t56 I felt I would never use all 6 gears with a .5 overdrive i believed it would be too much or if I went taller gears in the rear I would never use the first 2 gears. But that is just my 2 cents worth.
I mainly cruise backroads and rarely hit the highway so 6th would hardly ever be used.

The 5 speed I was warned I would blow the trans up with my small block stroker and w2 heads.