86 4runner

Hi all, I have an 86 4runner 5speed with the old 4y engine in it. After hitting the big 300k mark I'm now starting blow a little smoke. At first it was just a little but now I am losing compression and top end power. Its still ok to drive but fuel consumtion has increased. I know the easiest fix is a rebuild but I was wondering if anyone knows what engines are compatible as a bolt straight in job. I was thinking of converting to a 2.8l petrol or 2.8l turbo deisel as the old 2.2 is a little underpowered. I know I can do a v6 or v8 conversion but that invloves a lot of time, money and a great deal of missed offroad action while its happening. Any ideas on this one. thanks, Kevin