Can anyone figure this out (th350 sluggish)

[tmills213]

Guys (and girls)

I have recently installed a 383 and th350(w/ transbrake, reverse manual valve body) from a close friend. He had built it from ground up for a chevelle but it ended up sitting for a while(few yrs). I did not rebuild the carb as they had occasionally started it to ensure seals and everything would not rot out and it sounds healthy.

I tried taking it for a test drive and it seems to have no balls to it. It will shift 1 to 2 and chirp the tires and fine from 2 to 3 as well but seems like it is in a low gear and will act like it is engine braking at about 50-55mph. More recently I notice (before i had the transbrake solenoid hooked up) that N to 1 is giving a harsh metal clunk sound. thought it was maybe the solenoid flopping around but now that it is hooked up i have no idea whats wrong.

I changed the trans oil and filter today, very dirty from what i am guessing was the initial break-in? (i hope)

It is in a 64 c20 camper special. It isnt turning into the tire burner I anticipated. Anyone have any ideas????