l have an 82' subaru brat with the 1.8L ohv and a 4 speed transmission. I've been trying to find a replacement engine for it on ebay since l can not find any at the wrecking yard and see a few mid to late 80s engines. They are 1.8l and carbureted like mine is. But if I am not mistaken they are OHC. They look pretty much the same from the pictures as far as layout. Would anyone know how compatible the OHC engine is replacing one with OHV?

yes it would

The OHC engine is almost a direst swap, though the chassis rails r very tight, & may meed a slight ajustment/tweak. You can use the existing clutch of the ohv engine & the starter/gearbox mating area is the same. From memory even the engine mounts locate the same. The wiring is slightly different, but nothing a little time cannot sort out. The OHC has a pair of cambelts, but whilst it is a good idea to replace them if thier last change is unknown u need not fear engine damage if they fail. The valves do not hit the pistons. You may need to adjust the radiator fan mounting legs if clearance is an issue. All this assumes that u r putting a carb fed 1.8 in, as the injection engines r quite a bit more work due to the wiring. Make sure u get all the carbs/intake etc for the new engine as the old pushrod engines ancilliaries will not fit. u will also need the exhaust front section. l love the simplicity of the old engine, but the OHC does offer a useful increase in power! It is a bit of a fiddle, & requires a few (easy) modifications but essentially a very doable job.