[Chuck78]

The museum-restored 351C with it's 312ft-lbs torque@1600rpm is having shipping arrangements made to get to me next week. If I find a Magnum top end for it, that will be an extra 40hp (not 20 as I previously stated) & 8 ft-lbs (320ft-lbs @ 1600rpm). The HEI & Holley 500cfm may add a slight bit more power to that (moreso adds response and drivability).
I think a cam regrind with very similar timing but .020" more lift might be the 1st mod I would do if I desire more power out of the 351C/AX15 setup. Honestly the 305D with Holley 500 & HEI has plenty enough pep backed by a 1:1 4sp, 28" tires, & a 3.07 rear, but it's more the hauling torque and low highway rpm capability I'm concerned with. A 351C @ 312ft-lbs & 351E @ 320ft-lbs makes it seem to me that the Magnum top end with it's extra 40hp is less critical for my goals than a larger camshaft lift would be to improving torque output. I keep wondering if a 401M or 432 cam has higher lift specs than a 351 & if it is interchangeable.
I got a random email from a fella I have to write back to, I am guessing from the 67-72chevytrucks.Com or Stovebolt.Com forums. He said he has no problem with his modified 305A pulling a camper trailer after his mods to add 16% hp & 20% more torque. The biggest thing he said he mills the heads .120" (sounds like A LOT! I question intake manifold alignment at that point) to get 9:1 compression, and does a custom cam regrind and adds .020" lift for more of an RV grind profile. I may entertain milling .080" or .090" off the heads if I have them off (or find Magnum heads).

These engines make monster torque just beyond idle, so a 3.07 and a 5spd overdrive 5th turning 1375-1700 @ ~70mph in 5th would be awesome for my road trip drivability. I would like to add a limited-slip carrier to my rear end when I get it rebuilt, so I will then have the option to adjust the gearing to my adjusted preference of highway rpm once I have tested out the ax15 or similar Overdrive. I think the key would be figuring out how low of RPM the engine can go and still make enough power to overcome wind resistance at 70 mph. 312ft-lbs @ 1600rpm is mammoth, so I think one could drop to 1450 on the highway and not have to step into the throttle too hard to maintain that. Being able to slow down to 55mph and still have enough torque output to maintain 5th gear at a low engine RPM may be the actual target I need to focus on in terms of drivability vs a tunnel vision goal of lowest rpm I can efficiently run @ 65mph highway cruising in 5th