The oil pan NOT being below the frame thing could be a problem. You do want clearance and some protection but you will have other problems if you set it up to high...the trans will hit the floor or it won't be level to the rear end.
I can see needing clearance and protection for the oilpan, but don't they make some type of aftermarket shield that you can buy for just that purpose? If not, you may want to look into fabricating something yourself.
Your engine would have to sit fairly high to be above the frame rails. You could always fab a thick piece of metal to sit right under your oil pan and have it bolt from one frame rail to the other. Might have to have a somewhat crecent shape bend to it.
Yeah cause you have to change the oil sometimes Take a look at some ford pickups from 67-72 (other years might have them too but im not sure) they have a cross member below the oil pan that you might want to look into.
G,day from Australia! I have done a few 34 chassis in the last ten years and I have found the BEST way to set up an engine is to work backwards from the rear end placement. This means you will have already set your ride height and know where your pinion will be placed with an angle of about 3 degrees up. This and tunnel clearance will determine your transmission mount placement because the tailshaft should have the same angle front and back or it will vibrate (use a broomstick to replicate the shaft.
Don't forget that you need clearance for all that stuff like exhausts and radiator placement, not to mention the trans pan and engine oil pan clearance, if you have to modify the firewall and trans tunnel its much better than sitting on the side of the road waiting for a tow because a pothole just took out your transmission !
Once the trans is in the right spot lift the engine until the carby base is level both ways. Now make final adjustments and get a second opinion before you weld everything together!!