1989 GS500 engine: rebuild or replace?

[NW89gs500]

Hello,

I am new to GS 'life'. My son bought an '89 GS500 from a really nice guy last fall. Late this summer, the bottom end went out while we were on the track - collectively, we think we slipped a main bearing by the sound of the slap. I am an experienced home mechanic (cars, trucks and motorcycles), I have the tools, including torque wrenches and we have the manual. Provided the case is solid and parts are available, I am confident we can rebuild. But I am not immune to costs and time. So the question/s are:

1. Do we rebuild it or buy another engine?  I am torn between making a project of this with my son (and hoping we don't get in over our head) or buying a running engine (of unknown condition).
2. What year of motor/parts can I use: 1989-???

Appreciate any advice!

[slug]

1) I would rebuild. I knew nothing about motorcycles before I got my gs and I did a complete rebuild of the engine. So if you have experience i say, no you will not be in over your head and parts are not every expensive.

2) 1989-2003