I have an older Miyata 100 that I had converted to a fixed gear, being that it was low end, heavy, and cheap. The bike fits perfect, and (puts on flame suit) I recently ground off the cable guides and derailleur hanger. Used a dremel to get them off and a small sanding wheel to take them down flush.

I plan on repainting the frame with Rust-Oleum Metallic Sage also seen below and doing white detailing around the lugs.

My question is if the sandblasting will take care of the marks left from sanding the cable guides off, or if I should take more time to get those parts smooth.

Depends on how deep the marks are, the sand used, and for how long the sandblaster aims the nozzle at the marked parts of the frame. Bead blasting is also a possibility.

An interesting read...

https://www.magpiepro.com/jb/paint.htm

No, sand it down first. That way, you know that it will be smooth, and you will not have to spend extra time around that area, which could rough everything else up.

I think that is the color I used on my SS Iron horse conversion...it's beautiful. I'll try and post some pics. It is my first conversion and I did not cut off the excess hangers and stuff. I wish I had now.....

Easy answer. Take the bike and have it powder-coated (Painted). They will blast off the old paint rust etc and the powdercoat paint is about a 100 more durable than any rattle can paint job. Priduction bike frames are usually powder coated. If you pick a color that they are planning on spraying in the next week or two they will usually lower the price. just remenber that all the threads must be masked.....if they paint bike frames they will know this, if they don't find another shop

https://s246.photobucket.com/albums/g.../Iron%20Horse/

I may go back and cut-off all the bosses and so forth and respray. I really like the Rustoleum; I think it's better than Duplicolor and much cheaper..........