Re: 1994 F250 5.8 w/ standard transmission
I have that engine and transmission in my truck. (With aftermarket EFI) It will fit into your Bronco with some modifications.
1) The OEM EFI for those trucks is too tall to fit in the Bronco. You will need a Mustang or Explorer EFI setup which requires a 351 Lightning lower intake OR an aftermarket EFI like FItech.
2) Both the transmission (I'm assuming it's a ZF5) and the engine are larger and benefit from a body lift for clearance to the body.
3) You will need an adapter to mate the ZF5 to the Dana 20 transfer case or you could go big and get an Atlas
4) The ZF5 uses a hydraulic clutch system, which you'll have to graft into the Bronco.
There are plenty of people here that could provide specifics and pictures, as there are several running 351Ws and ZFs in their Broncos.
Performance-wise, the 351W/ZF combo is AWESOME. Tons of torque and wide gears really push a Bronco down the road with ease. I have no issues maintaining interstate speeds. You are only limited by your sanity. Viperwolf and I are running the same cam with different drivetrain combonations, but in both cases, it really woke the 351w up.