64 C20 engine and tranny install

[Desert dog]

My first post!
As mentioned in the welcome section, I'm helping a friend revive his truck. He has a '64 C20 and is wanting to install an '86 305 engine to mate with his original M420 tranny.
After some research we are planning to use an '86 168 tooth flywheel along with a '64 11" clutch kit' and '64 bell mounted starter. The engine was originally mated to an auto tranny so a pilot bushing will need to be installed as well.
The whole arrangement has been sitting out for a while so a cleanup of the crankshaft mounting and bolt holes will be in order.
I am debating as to whether to pull the tranny and bellhousing and mate everything together prior to installing them, or as he wants, try to stab the engine onto the tranny in place.
I would appreciate any feedback you would be willing to provide.

Regards,
Desert dog

[69 C10 LWB]

I’ve put 2 small blocks in without pulling the trans. If you leave the motor mounts on the frame you can slide the engine in no problem. You will need to support the back of the trans so you can get everything lined up. Don’t forget a new throw out bearing also.

[geezer#99]

I’d leave the bell and trans in place. Heavy trans to remove and replace. Bolt the flywheel and clutch in place. Use an input dowel to line the disc up.
Check to see if the 305 has the Drilled and tapped mount hole for the zbar in place. Some don’t or are located in a different spot.

[Desert dog]

Sirs,
Thanks for your replies. We'll try it with the bell and tranny in place.
Also, a great point re: the Z bar pivot. I'll be checking that tomorrow.