7/8/18 UPDATE:
Okay so this past weekend 7/7-7/8 I got the transmission and engine in for the most part.
I starter to put the engine in the truck on Saturday but was running into some issues where the engine wouldn't go in but nothing was visually hitting so I had a buddy come over Sunday and see if he could give me a second opinion and help me out.
We got the 305/80e in the truck for the most part yesterday afternoon.
We had to pull the heater core because my manifolds were hitting it even after I "massaged" it with my BFH (now I need to figure out if I want to weld a plate over the holes OR try to use the holes as a vent to channel air into the cab through the heater vents in the truck to help circulate some air in the cab).
For those who are interested a 4l80e will physically fit in the trans tunnel of a first gen S10 with only the firewall getting hammered to make room for the bellhousing before the engine dropped onto the mounts.
The engine sits about 1.5" from the back of the engine to the firewall and about 1/4 of the engine sits in front of the front axle (my motor mounts sit on the axle and they are positioned 3/4 forward on the block) I couldn't tell you about manifold clearance because my manifolds are totally wack and the are super wide in certain parts. The stock trans cross member works with the 80e but it gets moved back about 6" so you need to drill new mounting points for it on the frame. The driveshaft is stock length and fits right on the trans with the right clearance for the slip yoke but I had the Isuzu 4-speed which had a really long tail shaft on it so overall trans length on my truck is exactly the same (but the trans mount is on the back of the 80e while it was on the middle of the 4speed)
The passenger side mount of the engine mounts is about 1/4" too forward but I think that the driverside mount has enough play in it to allow me to rotate the engine around for that extra 1/4".
Here are some pictures:
(A careful viewer will note that the heater core is still in the truck in the pictures )
Now I have to run the lines for my gauges, figure out what parts of my stock wiring harness I can cut out and what I can reuse, and also put the core support and the front side of the truck back on (pictures to come of the radiator and core support modifications)
After that it's a matter of tuning it, making it look nice, and making some test passes and seeing what breaks...
If someone can point me in the right direction as for a base jetting and timing (and how to set the timing before starting an engine) so I cna start the engine and break it in safely I would appreciate it
Thanks for all the help you all have given me couldn't have done it without y'all's help,
Gabe