Oil pump swap

Stock replacement should be fine unless your engine has excessive clearance. It can be replaced in the car but it sure ain't easy. You gotta drop the center link to get the pan off. The way I do that is pull the entire steering linkage off (disconnect the tie rod ends at the lower ball joints, pull the pitman arm, unbolt the idler arm) so there's nothing in the way. Then take the dist. cap off cause you need to unbolt the engine mounts and jack it up as high as you can get it. When you do that the dist. cap may hit the firewall and break it. Keep a close eye on the dist. housing itself to make sure it doesn't hit the firewall. Last one I did was close but cleared. Taking the starter off isn't absolutely necessary but sure helps a bunch so you can get in to scrape off the old gasket material. I hope you don't have headers cause if you do the drivers side may need to come off, depending on how their designed.

What kind of oiling issues are you having?