I know this is the race section, I thought it would be appropriate here.
I am actually starting to consider a 636 ~655" pump gas engine, maybe keeps the revs down to 6000 ~ 6500 tops. A nice street motor.

So.

I don't know which car yet or car weight. Probably a large M/T street type radial. In fact, probably need a 4.56 gear to go with the 2 overdrive ratios.

With the right clutch, which I know will be absolutely critical, do you think one of the stronger T56 varieties will live ???

I know you can break anything if you really try. But if you drive it with a little respect for the mechanicals, will a T56 be OK ???

I was looking at Lenco too. But I really like the T56. Lencos have their own quirks and requirements.

How much power, HP ?

In my experience a standard T56 will hold up to -around- 750ft/lbs, for a while.

I think you would be good with a Tremec Magnum (TR 6060 internals)

Cab, I'm not sure, HP would be moderate 800-900, torque would be through the roof, at least 800 ft-lbs maybe ?

A stick with drag radials needs a slipper/ centrifugal clutch. If you’re not willing to go into the can with some frequency, I would suggest a different plan.

TRENDZ,
Even with a street driver ?

If all you’re looking to do is fry tires, than no. Something has to slip if you want to put down power. It’s up to you to choose if it’s the tires or the clutch.
Proceed at your own ri$k.

I had good luck with the McLeod street twin with organic discs. I was able to slip it enough at the dragstrip to run 9's on 17" drag radials.

I put a ton of miles on that car and raced it regularly. Would rebuild the clutch every couple of years.

That's true.
I've never driven a 600 cubic inch car. I don't know what to expect. But I can use reason.

The tires will only let the car accelerate so fast. Witness the F.A.S.T. cars. More "tire" will allow the car to accelerate quicker.

So with a given car and a given tire, there will be some limit of motor, beyond which the tires just break loose.

It's possible that, in this future car of mine, it won't even take 500 inches to spin the tires, and if that was true then 600 inches won't
accelerate the car any faster and it would be a waste of engine.

So to fully use a 600" engine, that car would need more tire bite. Going further, if you then had more than enough traction for a 600" motor,
this is the point where the clutch would need to be capable of slipping, because by definition the tires won't slip.

I don't know enough to know where this limit is. So, are you saying, to play it safe, to design some controlled slip into the clutch ? That would make sense.

I wouldn't dare use a radial tire on a stick car, never, never never

My mild 605 makes 764ftlbs@3500rpm, peaks at 4800@818.4ftlbs and holds over 800 ftlbs from 4100 to 5500rpm. I think you should rethink your transmission choices. Maybe a GOOD 727 with a gearvendors overdrive.
Also at that size you'll require a raised cam block, I could be wrong but I am unaware of a gear drive or a timing chain set for that block. A belt drive isn't really street friendly, kick up a small rock or trash and a lot of real bad things can happen. Rods and camshaft lobes can become very good friends if you know what I mean. My 605 has .060 clearance between some cam lobes and rods, I use a Milodon gear drive to make sure nothing bad happens. Dave