Although my 727 trans was recently rebuilt, whenever I start it cold (from an overnight or extended sitting/storage period), it takes a few moments (~10-15 seconds) for the trans to engage into the gear (say, simply to back out of the garage), then still it seems to have to wait another couple moments to actually move the car. After it runs for a few minutes it seems to be fine and I can drive away for my cruise (typically to a race or show). If it makes any difference, the trans is actually a 1972 model 727 that I've owned and run in the car since the late 1970s.

I have an auxiliary trans cooler (newly replaced), old BM Holeshot converter (bought ~1978), and a basic new shift kit (still fully automatic, but can shift manually if desired up/down). Fluid level is proper when warmed up. It's been like this for many years, even before the recent rebuild.

Car is not driven much. Any suggestions appreciated.