Cheaper than dirt 318 build
Until you get the motor you wont' know what parts to get.. a 85 will have 302 heads which is good.. it's also a roller LA block which is good.. but some like mine have the roller provision but came with flat tappets.. if you are lucky and yours comes with roller lifters it will make a big difference in how you build..
P.S. if you pull the dist you can see the lifters to see what you got..
Please quit repeating what you have read on the internet, I had a 5th ave 1985 no 302 heads or roller block.
If the OP heard the engine run, best way to get the truck going on the cheap is to just drop the V8 in and feel the difference. It will not be huge, but not slant-sick powered, not hating on slants, I have owned many of of them in various vehicles.
I can attest I had a 81 D-150 with a slant, drove it for alot of miles, it would get you there but it sucked, even with 4.56 gears, it would not pull snot out of a wet paper bag, the 833 OD has horrible gear ratios. Put the stock 3.55 rear back in it and sold it.
For comparison, I bought a 85 D-150 off my buddy, because I needed a vehicle quick. This D-150 was horrible, slant with an auto, 3.55 sure-grip, it was 100% reliable, started easy but was just **** for a truck, I think that year they were like 100HP, completely under-powered.
Now I have a 85 D-150 with a 440 auto, 3.55 rear, it is stupid fun, forget gas mileage, its more like giggles per mile.
All trucks I had were short-bed trucks, so the same weight.