Just joined over here,  been over at FTE for years.  

Hopefully I'm gonna build a fresh engine for my F350.  I've been planning on doing this for a good couple years.  (best laid plans!)
1st in need to figure out my rpm's I'm running out on the highway.  Gear changes make my speedo totally inaccurate, that, and the fact it bounces up and down about 10mph as your driving.  The 2nd is my weight.  It's a 350 dually flatbed, and the flatbed is homemade diamond plate and heavy.  Plus I do carry stuff on the back for show.
I have tires with 31in outside diameter.  The diff is running a 5:14 gear.   Plus I'm running an auxiliary tranny with a 17% overdrive.  Can someone help me with the formula for what rpm's I'd be running at 65mph?
I'm collecting parts and ideas.   I was looking at 312 cranks to stuff in my 292 block.   I was also looking at mummerts rods that convert 292 crank to a 312.   Anyone have experience with them?   I have a shortblock still together that has an ec crank in it.   I also have the running 292 still in the truck. So I have another crank there too.  I plan to bore the block to at least 312, maybe more.   I plan to still run the 2 barrel intake on it. It's running a holley 2 barrel with the oil bath air cleaner.   I'm running dual exhaust already, eventually I'm hoping to put rams horns on it.     I have a pair of ECG-D heads on the shelf,  and if I remember right,  the engine in the truck has C1TE heads.  

OK  throw some ideas and info at me
Pat