Rebuilding the 1.7L that came with my '72, and it looks like the case has been split before. A previous repair or rebuild effort left these scars on the case where the front pulley seal rides.

Any ideas on how to fix or at least prevent leaks?

One side of case:
Click to view attachment

And the other:
Click to view attachment

A little extra sealant should take care of it.

If you want to get crazy with it, have it welded and re-machined

Ok, cool, thanks. Any thoughts on a little JB Weld and careful sanding, or is that more likely to do more harm than good?

JB weld is never as welded as you would think. Sand it down so there are no rough edges to cut the seal and take the extra sealant route and I doubt you will have any issues.

Thanks, fellas. Sounds like the "right" answer is also a fairly easy one (I like when that happens). I'll go the light sanding and sealant route.

Yup. Smooth any burrs or sharp edges, and run it.