The trick is to support the door in the right vertical position when you swing it open to reach the bolts through the gap between fender an door.
http://www.eastwood.com/e-z-rest-door-hanger.html
I have used an engine crane with a couple of cargo straps holding up a full size truck door, rolling back & forth - same idea.
These swivel-head sockets make turning those concealed bolts possible: http://www.circlecsupply.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/3/4/34351.main.jpg
http://vintagemetalworks.blogspot.com/p/s10-t-5-to-gm-235261-adapter-plate.html
This part Looks like it works with the early T5 GM-style transmission mounting face, but they might know what works.
'90s Ford Econoline full size van.
I found a grandma's low mileage creampuff with the TV, fridge, and a bed in the back, less than 120K miles, Class III hitch and towing package under $5K.
It tows a 24ft camper, or a car trailer with ease.
foud this here:
http://www.carpartsmanual.com/datsuns30/DatsunFairladyZIndex/Electrical/CarHeater/ToJul73/tabid/1666/Default.aspx
There is a parts list by number. Looks like lever #15 adjusts the blend between VENT and HEAT?
Welcome and good luck with your swap.
All answers can be found reading this site, and in this book:
http://www.jagsthatrun.com/Pages/Datsun_Z_V-8.html
The JTR manual can be found on ebay for $30-$40.....cheaper than couples therapy......
links to TBI information might help with the swap
http://chevythunder.com/gm_throttle_body_injection_pg_1.htm
http://www.automedia.com/TBI_Fuel_Injection_Conversion/pht20001001fi/1
http://www.gearhead-efi.com/gm-ecm-pcm-conversion/tbi-efi-conversion.html
JTR.
...or...
http://www.northerndrivetrain.com/product/NEA-N2-2-899-1.html
http://www.drive-lines.com/parts1.php?pn=N2-2-899-1
http://sixstates.com/products/partdetails.jsp?part=N2-2-899-1&supplier=NE
found one on ebay once for $30.....