Yeah, I'm with Jimmy. If it's strictly for studio, there's not really a need for tons of watts, so you could take the wattage budget and reappropriate it to the tone budget (and probably look at something tube based, depending on what sound you're going for). A 100w or so tube head should be plenty to get those cabs moving for a mic to pick up. Or you could look at getting a nice tube preamp and a lower wattage power amp. For just studio use, a lot of the considerations for a gigging amp are either a lot different or just don't apply.
I don't get the rack mount thing either. If it's sitting on top of a couple cabs, why the need for a rack? Just more stuff to buy. If you rack it in your control room and have the cabs elsewhere, just means you need to buy super long speaker cables, which could affect tone somewhat. Don't overthink it.