You can sort of get a tone dialed up and run whatever plugins on it at the end, even compressors, and get the "color" of that tone. I've done it making IRs with the Waves SSL 400 compressor, Soundtoys Radiator, and other color changing effects saturation and compression FX after some cabinets, EQing, etc; and A/B'd them and ended up liking that I could have the color without the compression even better. It will sort of level out your sound because it will amplify it as if the cabinet adjusts those frequencies and should work good for cleans so wouldn't hurt to throw on a compressor because it will think the cabinet makes it come out level out like that and it's real close and the bonus of having your sharp pick attack back too. Kinda cool if you ask me. Just shape your clean tone with whatever plugins and see what you get, the only real way to know for sure, but I never tried an amp but should give you the amp's color somewhat too, probably even turn out better who knows.

As far as pre existing IRs, I would just try some of the ones in Recabinet or something. They're nice and level and have some cool colors, I use them on synths sometimes and maybe they're good on clean DIs, I dunno.