Oh man that IS nice!
Now if I'm not mistaken, I can't tell from the pictures, the car does NOT have a fuel gauge! That was typical for the original competition cars. Note the twin fuel pumps, and there should be corresponding fuel pump switches on the dash. One pump (primary) draws about 3/4 way down into the tank, the SECOND pump draws from the bottom of the tank, that is your 'reserve'. When fuel pressure runs low, uh, it does have a fuel pressure gauge, no? You switch to the secondary pump. There was some comment about a 42 gallon tank? Excellent! Again, thats what the Comp cars ran. Many of the Comp cars have extremely low rear end ratio's, 3.7 or something like that. With a top loader and 1 to 1 ratio in 4th gear you could calculate a 'top end' speed that is fairly low with that ratio, motor SCREAMING toward 7000 rpm at top end. Think 'short track' gearing which was the most common racing venue at the time. With such low gearing burning rubber and getting sideways coming out of the corners made for a hellish environment. Only men with BIG balls need apply to drive the car anywhere near it's potential, in or out of competition. No question, these cars were scary then and that hasn't changed. Along with those low gears came two things, extreme rpm at 'cruise' speed and ultra low mpg. Hence the need for a 42 gallon tank! The typical 15 to 17 gallon tank would be a joke.
With a more conservative 3.5 rear gear, top loader and classic 26" tires you can expect about 3000 rpm at 60 mph, 3.3 or so, maybe 2800 rpm. Assuming a reasonable carb and camshaft profile I would estimate 10 mpg is possible at a steady 60-65 mph. Could EASILY be 6 mpg with a fat carb, radical cam and a little heavy on the 'go' pedal.
Of course it's a 460 and I don't know much about that setup so give us an update when you figure it all out. Details man, it's all in the details!
Hmmm, modern style fuel pumps, subtract points at the Concours de Elegance. Of course the original style pumps might run as much as $1,500 per unit, so I'll let you slide on that one. Now, can we get some side oiler type fakey doo valve covers for that 460?