Nice project gun.
It shouldn't be about the money,,if it was you'd never do any projects.

Micro Sight made a front sight that required the blade to be filed off down to the base and was then pinned in place with 2 cross pins. Might be what was on there.
The matching adj rear that they sold required a single drilled and tapped hole just forward of the fixed rear sight down in the groove,, not that it matters here.

I looked for a base, I have a Kings front site base but it's for a pre-war magnum. It pins to the rib of the magnum bbl w/a small keel like the blades do do the base.

I think I'd press fit pins into the holes, trim them off and fit a new blade S&W style anyway.

Should be a fun shooter.