Agree that that most headers will not slide between the shock towers when pre-installed on the motor.
I remove/install the 351w motor/tranny as one unit in my similar, but smaller 65' engine bay. I raise the car so that the frame is maybe 1 1/2' off the ground-just enough for me to crawl under to attach the tranny mount once everything is in place. Too high and your hoist might not work to get the motor over the radiator support (assuming it is the common portable type.)
A lot depends on how you attach your motor to the hoist. I use a homemade motor lifting plate--a simple HD hook attached to a plate of metal and securely bolted to the intake manifold. I also use a short piece of chain in a small loop to attach the hoist to the lifting plate. It works great with my combination. There would be some weight differences on the rear of the motor due to a C4 vs toploader situation, but that scattershield/clutch setup that I used is very heavy too.
Look closely in the following pic and you will see that I used a piece of cardboard against the firewall to protect it. The transmission is pushing up against the firewall and I use that to my advantage. Some may feel squirmish about that but in my case the pressure isn't as much as you might expect as I can still push the tranny down with my hand. It is all in how you initially balance the motor. You can also see how much stuff that I pre-install on the motor when it was on the engine stand. The oil pan is within 1/8" of clearing the radiator support:
I tried one of those levelers once and the handle always seemed in the way. The thing is laying in the corner of the garage and hasn't been brought out since.
A final shot with the engine in place an the headers and such are being bolted on. You can see that there isn't much space between the motor and the shock towers.
The headers were snaked up from under the car, which is the only way that I can get them installed. The hoist is used to move the motor side to side to give additional clearance for each header. You will have even more room in your 69' bay to jockey your motor around.
The installation shown above is a one man operation and it does work well for me. I recommend that you have help though as a second pair of hands/eyes are more than helpful for the inexperienced.
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Dennis
65' STANG (3330 lbs), 393W, Toploader 4 Spd, 4:11, AFR 205's, Vic Jr. Intake, CI SR Cam, 950dp, 10.6 CR
11.21@124.0 al naturale
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