slant six cranks but won't start

OP you haven't said a thing about what you have tested (besides replacing parts)

1...Have you tested for spark? IMPORTANT. "Rig" a test gap or overgapped plug to the coil with a WIRE core wire and not a resistor wire. Crank using the key and check for spark. Should have a nice blue snappy spark at least 3/8" and more typically 1/2" long

2...Fuel? Has this BEEN running? Or parked/ stored? Is the fuel stale? You SURE?

3...Are plugs fuel fouled?

4...Have you run a leakdown/ compression test?

Diagnostics are IMPORTANT and throwing parts at something, whether you can afford it or not is no way to "fix" something.

(Example, you "throw" a bunch of money at tuning it up---which it may or may not need, only to find something "else" in the end like a poor connection/ path from the ignition switch to the ignition system--or maybe even a bad switch.)

we do start it from the key working on compression test spark plugs new not fouled never been running parked long time not using gas tank NOT THROWING MONEY AT ANYTHING we are taking it one part at a time to diagnose the issue your statement is a bit insulting! put questions here because we are stuck and thought we might get help with something we may have missed!