Hi Capt,
It's a little difficult to say, since your car is a TR3A. There is some variation, car to car. On a TR4, I'd say 195/65 would be no problem (unless the wheels had some strange offset). So, unfortunately, about the only thing to do is give it a try and see if they fit okay.
Glad to hear that you opted for the stronger 72 spoke wheels. But, you didn't say what rim width. That will, in part, dictate how wide the tire you fit can be.
Be sure to fit the wheels onto the car and test carefully for any clearance issues *before* fitting any tires. Often once tires have been fitted, wheels can no longer be returned for a refund.
When you do go to fit up the tires, try to find a shop that's experienced with wire wheels. Their experience might help avoid problems (such as leaks) and they may check for balance and true before fitting the tires.
FYI, The Tire Rack has customer feedback and reviews on most makes and models of tires, right on their website. The more common/popular models of tires that have been around awhile have accumulated a pretty good mass of info. At that site and/or the manufacturer's website you'll find specifications such as recommended rim width, diameter or the tire, tread width, cross-sectional width, etc. You might find this useful.
A problem you could run into is getting the tire and wheel to fit into the spare compartment on the TR3. It's a pretty tight fit even for the original narrow wheels and tires, so you may need to run a narrower tire on the spare (or let the air out of a slightly tight fitting tire... but then what's the point of having it in there!). I think the earlier TR3 had a rather smaller spare compartment than the later, but I don't have either car so can't really say for certain.
Keep us posted.
P.S. Are you converting from disk wheels or just replacing old wire wheels? If converting, you have fitted adapters I'm sure. Just be sure to shorten the lug studs as described in the manual, or they will inerfere with and damage the wheels the very first time they are installed.
An alternative to shortening the lug studs is to fit wheel spacers behind the adapters. This allows reinstalling any set of disk wheels (or mags such as Panasports) in the future, without having to replace the lug studs with longer ones. However, the 6mm of additional width *might* cause clearance issues on a TR3 (or it might just as easily solve clearance issues, if they are inboard at the springs or a-arms).
OTOH, if replacing old wires and using old adapters, try to check for any play or wear in the old adapters. The splines do wear over time.
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