I've been thinking about doing a drop bar conversion on an old fully rigid mountain bike.

I'd like to do this for cheap (initially) so thought I'd not get new shifters and just run as a single speed right away. On the front I imagine I can just remove the derailleur. I guess I'd like to keep the rear one on for chain tension. Can I adjust it to a specific gear without a cable pulling on it?

What would the cheapest way to keep the ability to shift on such a bike after drop bar conversion?

I am aware that brakes can be an issue as well. Is it right that I could put on these Tektro RL520 levers that are made for mtb v-brakes and be done with it?

This is the bike I have that I could convert. I'm concerned about the stem. It seems a shorter stem would be better to put a drop bar on. I may try to find a cheap CL bike to work on.