i believe they are actually standard. the block is standerd but some of the crap bolted to it is metric. jeep is bad about it. so is ford and chevy with their small blocks.
i believe bolts are 1/4 course and 5/16 course.
if it threads directly into the block it's standard. if it threads into something bolted it's probrably metric,
I think they are standard as well. And two different sizes. I had to replace a lost bolt for the pan to timing cover and it was different from the others. So two sizes if it's like the 92-91 4.0.
Anything that threads directly into the 4.0 block or head is standard. 1/4 and 5/16 coarse sounds right. Beware of things like the starter, where one bolt can be metric and one can be standard. Water pump to block is standard, water pump pulley is metric. Valve cover bolts are standard too. It's just that 7/16 and 11 mm and 1/2" and 13mm are so close people don't really notice unless they're trying to retap a hole... I think there is one unused hole on the driver's side of the block that may be metric. It's the first and only I ran into and that was when I was installing Brown Dog motor mount plates.
the four corner bolts should be the 5/16, all the others are 1/4. a couple of them are weird 1/4 studs because a bracket for the o2 sensor or trans lines bolt to them, so make sure those go back in the right spot.