1990 Transmission needs replaced, what brand do you recommend?

I'm in the planning process of swapping the stock 305 that came with it for a 350 with around 250-275hp (see other thread.)

When I changed the fluid I noticed some clutch dust and some metal shavings and half of a dime sized washer chunk. So seeing as it's going to need some work soon, I figured I'd invest in a new transmision that will cope well with a 350.

The current tranny is a stock 200-4r. 119,492 miles.

What brand, or what type?

If you're going to run a 350, build up a decent TH700R4 or 4L60 (a 700R4 with the auxiliary valve body - saves internal parts by cushioning engagement in forward or reverse). You will need a driveshaft for sure. If you get a transmission that also has a mount provision on the tailshaft cone, you can still use the TH2004R crossmember. If not, you will need a crossmember for a TH700R4.

Thanks for the reply, sorry I should of stated I'm asking on both brand and type.
I hope you won't mind if I pick your brain a little.

Why the 700R4 over the 200-4r?

What my research has turned up so far is a 2004r has slightly better MPG in over drive, and the 700r4 has a lower first gear.

The 4L60 has better reliabilty over the 700R4 from what you mentioned correct?

I'm currently looking at Bowtie Overdrives level 2, but am far from convinced they're a good buy.

I really don't see this car going over 350 hp any time soon.

Thanks for the reply, sorry I should of stated I'm asking on both brand and type.
I hope you won't mind if I pick your brain a little.

Why the 700R4 over the 200-4r?

What my research has turned up so far is a 2004r has slightly better MPG in over drive, and the 700r4 has a lower first gear.

The 4L60 has better reliabilty over the 700R4 from what you mentioned correct?

I'm currently looking at Bowtie Overdrives level 2, but am far from convinced they're a good buy.

I really don't see this car going over 350 hp any time soon.

On a Caprice, you learn to really fall in love with that lower (3.06:1) first gear. It gives your car newfound life. The 2004R can be made as strong as a 700R4, but it's more expensive. It was also made for 8 years, while variants of the original 700R4 (4L60E, 4L65E) are still in production after 26 years. The difference between a 2004R and a 700R4, economy-wise, is really non-existent. I say this because my car used to have a 2004R in it. I've been able to determine economy with both, and there was no discernible difference.

The 4L60 is a later-model of the 700R4 - it has several valve-body and strengthening improvements over the earlier design. I denote transmissions made before about July 1986 as being 700R4s, those made after as 4L60s. The main difference, again, is the front pump and aux valve body - which is a spool valve and an accumulator that softens engagement out of neutral or park. This saves parts, but it also makes the engagement smoother from the driver point of view - without it, 700R4s have this habit of engaging in reverse so hard, that the back wheels can actually spin a little (chirp, bark) when the transmission engages. The aux valve body eliminates this.