Twizza, if you´ll take advice from a bass-playing not-exactly-speaker-expert 😯 …
1) I think Lee´s right. Your amp doesn´t “know” one speaker from another so the T will take it but the H will possibly blow on full. HST, I gather that the 30W handling was very conservative and they can take 50 (no comebacks on me, though 🙂 )
2) If in a metal band, and rich enough, then the full stack with two 4×12″s allows anything you like.
3) Sticking with the single 4×12″, I have read somewhere that a pair of Ts and a pair of vintage 30s is a nice combination of “hair-shirt” and “mohair” response. For metal, though, the quad of Ts might well suit you best.
4) You don´t say whether the head is SS power or valve (forget about the preamp for now). As I (mis)understand it, with SS power, you don´t want the speaker rated too much higher than the amp. If your amp is pushed full on (at 200W 😯 ) and into clipping, then your cab will be seeing a square wave. This is driver murder. With a valve power stage, a 300W cab is no problem; even desirable. Valve amps clip softer, and the cab can capture this. Also, some think (I´m not going to try and argue) that valve amps have a transient attack well in excess of the rated power but sag quickly, whereas an SS will just putout the signal amplified to whatever value the vol knob was set at. It´s some people´s expl of why a valve amp ´seems´ louder than its rating.
I ramble, but maybe some of this is of use. One last thing. Search for the gear used by Mick Ronson (Bowie´s guitarist). He used a 200W Marshal Major head, and his cab setup may be of interest. Finally, Lee mentioned the impedance. Wiring the four speakers up to fit the output impedance of your amp is very important. Done wrong, this can fry all sorts of components. More on this turgid aspect available on request…