3406B NEW OWNER QUESTION

I have a 04MG 3406B 425 in a 1990 379 and a 13 speed. Truck had been sitting prior to me buying. I have been working on old gal, runs, drives, sounds good. My issue is, while going through the lower gears it seams fine as in it gets up to speed but doesn't set you back like an e model and when i get to 5th or 6 gear it really takes off. The best way i can describe it would be like hitting the powerband of a 2 stroke dirt bike. Does this all sound normal? I know it doesn't have the torque of a new engine butt it seems a little lackluster on the lower 4 gears and the sudden get up and go seems odd to me.
I have had pump and advance overhauled, new fuel lines, new intercooler(boosts to about 27psi) new filters. It did this prior to pump work also.
I have not had a trailer on it yet and this is my first mechanical engine and still a work in progress.
Is this normal?
Thanks for any help,
DAN

 

Thanks @wore out . Good to hear im worrying about nothing.
What kind of idle rpm settings are you guys running? Mine is about 600 but with the throttle control turned up to 700 it smooths out. Should I idle her up or leave alone?

 

I'll idle the old gal up. Seemed a little low to me. When I put pump back on , I set it at the same rpm as previous setting. Previous owner said he idled it down to slow down his backing speed.
If you have any advice on the B model, I'm all ears. Its my first one. I miss the cruise but so far i like the engine and its lack of sensors, wiring, and plastic parts.
Thanks for your help.

 

10-4 will do.
Thanks again for your help.
DAN