We offer performance lock-up TH350C torque converters with higher stall speed ratings (2,000 / 2,500 / 3,000 / 3,500) if you're interested in using that transmission and would like to have a performance-oriented torque converter to use with it.
The TH350C can be built into good performing and durable transmission for a street or mild street/strip car. All the commonly available performance friction materials and intermediate sprag upgrades for the TH350 also fit the TH350C. TransGo offers a valve body reprogramming kit that works well and provides dramatically improved shift quality and transmission durability. You can install a toggle switch to manually control the converter lock-up feature so that you can control the engagement/disengagement. Also, the TH350C can be converted to a non-lock-up transmission if necessary with the installation of the earlier style TH350 front pump, input shaft/forward drum, and valve body.
The lock-up feature is actually a pretty neat thing to have when using a high stall torque converter on the street. If you have a combination that requires higher stall speed (3,000+ RPM) and you want to drive it on a regular or even daily basis, especially regular freeway/highway use, the lock-up feature will allow you to have all of the performance advantages of a high stall converter while also having improved fuel efficiency over a non-locking converter as well as reduced transmission operating temperature.
Also, for the 200-4R and 700R-4 guys, I wouldn't ever run a non-lock-up torque converter in a street car unless you were running an OE-style low stall torque converter or running a mismatched overall combination with a 2-series rear gear ratio and a large cam profile and/or large runner cylinder heads/single plane intake manifold. A lock-up torque converter does not offer any significant performance disadvantages in a street or mild street/strip car so there really isn't any point in giving up the additional fuel efficiency and reduced operating temperature.