There is no need to guess and fight with your engine. Eliminate as many variables as you can Get right down to basics
COMPRESSION. Engine needs to be in good enough shape to run. I would guess a poor old oil burner would still run down to 80? PSI maybe less. So run a compression check / leakdown
FUEL Engine needs good fresh fuel. If this is fuel been sitting for awhile get some fresh fuel and prime right down the carb throats. On any fireup where I think this is a problem, I rig a siphon from above in a "safe" container hung from above.
SPARK. Engine must have GOOD HOT spark and at the right TIME
A SIDE NOTE. This includes CAM TIMING. Is there any question the cam might have slipped time? You can check this in several ways. First, wrench the crank back / forth with a wrench and watch the rotor, and see how far you can move the crank before the rotor turns. After you do this 2 / 3 times you'll "feel" the chain play
LOOK IN the service manual. There is a procedure in there to check cam timing, if you have a "hotter" cam you can look up the specs and check intake opening event which is usually close to TDC some degrees.
SPARK AND TIMING
CHECK spark. "Rig" a spark gap and check spark right at the coil. Should be a nice hot fat spark about 3/8--1/2 inch
TIMING. There is NO NEED to "guess" about 180 out on timing. The ONLY exception to this is that a couple of members on different forums have somehow gotten reverse grind marine cams and that can certainly throw a wrench
TO CHECK timing do ONE of two things.
METHOD ONE
If either valve cover is off, bring the timing marks up on TDC and see whether both no 1 or both no 6 valves are closed. Look carefully because on one of these, they will be "equally" (or about) equally open. IF IN DOUBT wrench the engine and see on which cylinder, 1 or 6, both valves move.
The cylinder on which both valves are closed is the cylinder which is FIRING and the one which the rotor should be indexed to. So if both no1 are closed and the rotor is pointing to no6, it ain't gonna run. Read on for the rest of the story
METHOD TWO
One popular way is to remove the no1 plug, stick your finger in the hole and bump the engine around until you feel compression. You might have to do this a couple of times. When you START to feel compression, watch for the timing marks which are "coming up." Bring the engine NOT to TDC but rather to where you want initial timing. On a bone stock 318, you want at least 10 BTC. On something a bit hotter cam, you want more like 15, and maybe 20BTC
So set the timing marks at this point. Now with the vacuum advance "in the middle" of it's movement range, remove / replace the cap until you can determine by looking, to which plug tower the rotor is pointing. The rotor will be (small block) approaching the cap tower going CW. THIS TOWER is where you want the no1 plug.
NOW rotate the dist. CW (retard) a bit and slowly return it CCW (advanced) until the reluctor tip is centered in the pickup coil. When you get good at this, you can even "wiggle" the thing a bit with key on and produce a spark.
IF YOU have points, do the same above, but rotate back CCW until the points just open. Determine this with a lamp, meter, or with key on, look for a spark.
SNUG down the distributor just a bit.
If you have done the above correctly you do NOT have to fight with the engine. Make sure the plugs are clean and dry. Make sure the cap / rotor is clean, dry, has no carbon tracks. Make sure you have good plug wires and a good coil wire.
If you have done all these things it will explode to life IMMEDIATELY
