I have a couple of Oktava MK-012's that i use for my indoor stuff and i really like them for the price. I think they are about $220 each. I've tried a few other low cost condensers, but i always end up coming back to my Oktavas.

The Rode NTG-1 is an interference-tube shotgun and shotguns in general are not the optimum for reflective interiors. For that I'd strongly suggest a hypercardioid. The problem is your $300 budget limit About the only hyper under that line would be the Oktava MK012 at about $250. Then you'll need to add a boom, shockmount, and cables to that. Frankly I'd prefer to try to get my hands on a couple of hundred more bucks to play with and go with the AKG Blueline SE300B/CK93 hyper, costing about $475. There are a number of other hypers that would be excellent choices for interior booming but they'll be even more dear.

One of the very few mics that are equally good both inside and out is the Sanken CS3 - it looks like a shotgun but actually gets its directionality from a different physical principle than interference-tube mics. The downside is it's well out of your budget and would set you back about $1700.

You really should give some thought to renting the appropriate gear.

Referred to by some as the poor-man's Schoeps, the Oktava's, at least some of them, (Russian quality control issues & Chinese knockoffs) are quite nice sounding. The drawbacks are excessive handing noise, even with best shock mounts, and the slightest movement in air will create LF wind noise, so a foam windscreen will be necessary even indoors in most instances. I use mine for stationary boom mounted interviews only.
Very nice for drum overheads as well as acoustic guitar and choirs. Sounds very similar to KM-83/84s IMO.
I would recommend getting them from 'The Sound Room', who hand-picks them, tweaks, documents, and matches stereo pairs. Well worth the extra $100 per mic or so.. Or do you feel lucky?
PS- I am in no way associated with "The Sound Room" except by location proximity only.