Jim makes a very good point, do you trust this motor? Has it been assembled well with good parts? Is it in the condition the previous owner claims it is?
What ever you decide to do, when you get ready to start it for the first time you must consider that your basically new-old-stock motor probably has a flat tappet camshaft in it that requires breaking in, and rings that need to be seated. Remove any oil that may be in the pan and use Valvoline VR1 Racing oil, 30 weight. It has good levels of ZDDP in it. ZDDP is getting harder and harder to find in motor oil, and is essential to breaking in the cam without destroying the lobes or lifters. In lieu of Valvoline VR1 oil, use any single vicosity 30 weight oil that is labeled HD on the container and has an API service rating of SJ. If it doesn't say SJ, don't use it.
Camshaft lobes are splash lubricated and the rule of thumb for breaking in a cam is to run the engine at 2000 rpm or higher to get enough oil splashed onto the cam lobes to lubricate them properly.
The proper way to seat rings is to slowly accelerate & decelerate the motor during the first five or ten minutes of initial operation.
So, the first running of the motor is no time to be fussing with the carburetor or ignition, or getting air out of the coolant system. You have to focus on camshaft lubrication and ring seating.
Remove the thermostat, connect the coolant outlet pipe to the motor, fill the coolant system as best as possible with the rear end elevated, lower the rear end and elevate the front end to purge air from the motor, lower the front end, re-install the thermostat & coolant outlet pipe. Top off the swirl tank one more time. Borrow a known good carburetor & install it on the motor. Eyeball the ignition settings as close as possible. (If you want to be real fussy, put an infra-red lamp on the oil pan and let it sit long enough to heat the oil inside the pan.)
Start the motor, run it up to 2000 rpm immediately, and then slowly accelerate the motor to 6000 rpm, decelerate it back to 2000 rpm, and repeat. Do this for ten minutes, afterwards let it sit for another ten minutes or more idling at a steady 2000 rpm to finish breaking in the cam.
The rings are at least 90% seated at this point.
Drain the oil from the pan & refill with more Valvoline VR1 Racing oil, replace the filter too. Now that the cam break-in and ring seating proceedure has been accomplished & the oil changed, the next step shall be to dial in the ignition and carburetion (dyno time!). After the carb & ignition are tuned you may drive the car normally, babying the motor will accomplish nothing. Run the motor for 500 to 1000 miles then replace the oil & filter again.
cowboy from hell
