The S10 converter was looser than a stock converter, by about 1000RPM... I was running a pretty big cam 238/246 @ 050 so it didnt like idling below 1100RPM much. There was like a 650RPM drop when put into gear.
If your heart is set on a 700R4 best of luck to ya. You might luck out and it'll last a long time. The thing that gets me is people will break their 700R4 then spend $1500+ for a "bullet proof" one, then have that break, so on and so forth. If you think about it, the $1200+ you'll be saving in the long run could go towards the extra gas you'll be using without O/D. Just food for thought, I made the same mistake of putting a new motor behind an old stock 700R4 thinking it would last atleast a little while, I was warned by many that I might as well replace it while it was apart but I had to learn the hard way. It'd especially suck if your not very mechanically inclined so you'll have to pay someone labor to pull/install your trans
When/if it breaks and you decide to put in a TH350 lemme know, I'll help ya
Anyway, I think you definately need a converter for that motor. I'd rather have to ease into the throttle to keep traction than to stab it and have the car putt along until it reaches 3000RPM. With a 2800-3000RPM stall and all the suspension work you plan you shouldnt have TOO much trouble hooking on street tires. If I footbrake my car to 2000RPM then quickly go into the throttle (by quickly I mean quick, but not instantly stabbing it) the car will hook pretty good on street tires. Now, if I stab it off idle even on slicks it spins violently because the converter flashes to like 4000RPM. This is probably with 100HP more than your motor will make and on 100% stock suspension.