What is a good stall to go with a 3:23 Sure Grip?

There is a company out in Langley BC called TCS (https://www.tcsproducts.com/) that builds them from scratch to match your engine spec. Been in this particular business for over 60 years apparently, so a lot of expertise there. A little more expensive than usual, but might be worth it to get something that helps me get the most from the engine

I edited my first response regarding the intake pictured...

I deal with and have dealt with this FOREVER. People will spend 10K+ on the biggest baddest engine they can build, then put the cheapest junk $200 POS converter behind it. Then complain that the car doesn't run right.
In an auto car, the converter is basically the single most important part of the combination. Gears, tires whatever... converter!

TCS is good and in your country. I've bought more than a few things from them over the years.

IIRC the roller cam in that engine is in the 230's at .050 290adv and 500+ lift. It's going to want 3500+ for flash