3.73 gears in 700R4 ?

[TomsResto]

So I know the whole "what RPM" will I be turning question is a complicated one with several contributing factors ... I now have a 275/40ZR19 rear tire behind a Ramjet 350 (350HP, 390TQ) and 700R4 with 3.41's in a GM 10 bolt.

RPM's are really low at cruising speeds (1750RPM at 60mph) and she'll bark a quick patch on dead stop before hooking up (nearly 11" strip of contact patch on each wheel now on Michelin Pilot Super Sport 300 treadwear) but I'm considering going to 3.73's to have a little more "throw you back in your seat fun" when I get on it ... but dealing with the age old "but how much more R's will I turn when I get out on 2 lane highways, etc." issue as this car is a cruiser before racer (and this time of year with fall colors intend to be doing quite a bit of road trip cruising)

I know the 700R4 has a tall "overdrive" 4th gear but I haven't yet come across an online "calculator" where I can throw my current setup in and see the result that matches what I see on my tach to have confidence if I leave everything the same and change the rear end ratio to see my new 60mph rpm. Does such a calculator exist and I'm just missing it? ... is it affected by GVWR?

Does anyone out here by strange chance have almost same/comparable config with 3.73's that can share what they are turning at highway RPM's?

Thanks,
Tom