Another Torque converter question or 2

[motovate]

OK - 1972 Chevy K20 4x4 with a GM crate engine rated at 350HP/350TQ. Engine has been in truck for years, has maybe 20,000 mile on it, runs good. It had the stock SM465 4 speed truck transmission in it and I just got tired of shifting it.

I have a 1989 Chevy V2500 4x4 Suburban with a stock replacement Chevy crate engine in it - maybe 200 HP? Turbo 400 transmission that was rebuilt maybe 20,000 miles ago with a stock type replacement torque converter - worked good - as expected. Not a lockup type of tranny/converter.

I took them to a shop and had the t400/TC pulled from the Sub and the sm465/205 TC pulled from the K20 and the T400/TC put into the K20 using all the Sub stuff. Flex plate/torque converter, etc. I believe they used the same conveter - there's no reason not to have but they screwed up plenty of other things so that there is no trust they didn't switch it for some reason.

Here's the issue. Now in the K20 when I start it up - let it warmup for a few min then put it in gear - any gear - but reverse comes up first it slams HARD into gear. Put it in neutral then drive and it hits HARD. Bangs hard into gear and jumps. One of those better have the brake on or it's taking off things.

I thought it might just be because the choke was on Hi Idle - so I wait until it is fully warmed up and off Idle but maybe idling 900-1000RPM- still does it.

When I drive it it seems to shift fine as expected but at a stop it still wants to take off. So I lowered the idle until it will barely keep running and it seems to lighten up some but not go away.

Obviously ????? the torque converter is engaging much sooner then it did with the 200HP engine. I'm just real surprised the stock converter engages so quickley and hits so hard.

Any Ideas on where the stock converter is supposed to engage RPM wise? Any Idea on what I should look for in a new torque converter RPM wise.

It's not a hot rod - just a more powerful engine.

Thanks

LBM