I have a 72 350 stocke except for Cam and Headers 1 1/2 block huggers in a 78 Jeep CJ7 I have restored, I did not rebuild engine but had heads checked and  new seals ,valves laped,all new gaskets and seals,have oil leaks on passenger side maybe valve covers,but back of engine around intake gasket is pouring oil but gasket and sending unit seem dry? also looks like main is leaking alittle and timing cover to oil pan is dripping seem to leak worse at high rpm when I ran it hard,oil pressure seem ok idle 20,40-50 at 2000. Also if I pull this engine agian I have a new set of Edelbrock E-Tec 200cc 64cc vortec heads that I bought to go on a 383 I have plans for but not cash,can I put these on a stock engine , I have 262 crane cam now ,could change this or what someone may suggest. And anything someone can give me advice on.  

Old SBCs and oil leaks are good friends. Leak on the rear can be rocker cover or improperly sealed intake or no gasket under the distributor. Or the distributor does not seat on the manifold because of head or deck milling.

Leaks around rear seal are common, to fix you've got to drop the pan and crank; even after that exercise there's no garrantee with rope seals.

Leak around the timing cover is probably dimpled bolt holes preventing the cover from sealing into the gasket. More force on the bolts (same with rocker covers) only makes leakage worse.

The solution, or at least a partial solution, is to remove the rocker cover and the timing case cover and gently dolly the dimpled bolt holes back flat. For the rocker covers there are shaped bars that can be purchased that go under the mounting bolts which both reinforce the bolt hole so it won't dimple and are shaped to apply force over a longer length of the gasket rail. For the timing cover after dollying the dimples out, get fender washers as thick as you can find, scribe the shape of the cover at each bolt location onto the washer. Then file or die grind the washer to that shape. Then install each under the bolt and gently tighten. Except where silicone is required to insure a seal such as the corners of the intake where it meets the head, I like to coat my gaskets with grease or anti-seize. This helps the gasket to slide around as the retaining bolts are tightened making a good seal with out gluing the things to pieces of structure. If you must glue, do so to the removable part as it's a lot easier to put covers on the work bench to hack the gasket off than it is to reach many places on the block when it's in the vehicle.

Lastly the leak on the rear could be warpage of the head or block or a loose head bolt on the back side where the oil return is, so check out the torque on the head bolts first. 

Oil blowing out gaskets at high RPMs shows insufficient breather area or too much blow by. Either builds a lot of pressure inside the crankcase and under the covers.

You can do the E-Tecs anytime.

Oil on the back could also be blow off from the crank if it's leaking enough to where the flexplate is flooded and rotation sprays it all around the inside if the bellhousing. I will ooze out along the interface and wash back down the outside of the bell housing.

Bogie