Need Help---Cruising RPM's for SBC and TH350

My question is one of suitable RPM at a given cruising speed. This doesn't search well so let me explain. My choices are limited because I have a TH350 (1600-1800 stall plus cooler) and one to one final drive.
Car is a 1975 lb salt-flat type thing with 31.5" rear tires, 270HP SBC with 3 1/2" side pipes and 3.57 quick change rears. At 55 mph it's 2100 RPM and 2280 at 60 MPH. It's small, low to the ground and I just use for local trips of maybe 40 miles a day, 1500 a year. I rarely "cruise" above 55 MPH, never get on the interstate and the side pipes are always barking.

I'm looking for a little more excitement and thinking of changing the rear gears to maybe 3.90 or even 4.11. That would mean my limited 55 MPH cruising would be at at 2313 RPM for 3.90 and 2415 with a 4.11.
At 60 MPH the 3.91 is 2520 RPM and the 4.11 is 2643 RPM.

What do others think of a 3.90 or 4.11 in the above situation and cruising at those RPM's? What's an "ideal" RPM range? Questions I have would be the wisdom of that RPM range, trans heat and noise from the side pipes. The quick change makes it easy if I guess wrong and I don't care about the gas.
This topic didn't search well (with TH350) and I'm looking for feedback from others who may have run a SBC with lower rear gear or even have an opinion. Any info would be appreciated.

 

well with a car that light you shouldnt need too low of a gear or you will just be burning tires off (seems like you should already be) even with those tall tires. your SBC should turn 2500-2600 rpms fine esp if you're not gonna be out on the road for hours doing it. honestly i think either gear will work for what you want and doubt you would be able to tell that much of a difference between the 3.90 and 4.11s. good luck

 

ttt

 

I've got a mild flathead in my roadster with a set of 3.48 gears in the QC and it is almost more fun than I can take! With 4.11's you won't be able to keep the tire on the pavement. My buddy Turkeyjerk has a built 377 SBC/th350 with 4.11's in his T and it's just stupid scary. It cruises pretty well even at 65, I'd say if you're not doing a lot of highway driving, go for it. Heck it's only a quick change right? 15 mins... Try it and find out! I'm not sure what 3.57's equate to the other way around, but my 3.48's are 4.11 flipped around. BTW, my flathead ABSOLUTELY did NOT like the 4.11's on the highway one bit!!

 

Mine is a 4.6L Ford.. Cruisin' rpm's in 4th @ 45 mph is like 1800-2000 rpm (I never look) with 3.55's out back. 5th gear is overdrive.

 

i have a 350/350 combo with 2.79 gears , 29" tires and a 2000 convertor...i cruise around here aroud 1800 or so , 2500 ish on the expressways at 75ish. would like to step up to a 3.25 for a little more 60'......