I bought this as a spoof and for no other 'research purposes'. I'll be honest, I'm a little embarrassed to have this sitting on my desk.
But it is pretty funny if you get a little creative and don't just use it as a body replacement for the first 30MS girl "Rishetta".
The main body (not counting the thighs) are a little longer than your average HG gunpla kit. Thing is, the pegs used are compatible not just with 30 minute missions kits, but a large array of High Grade kits.
While it's not meant to be, you can use some legs from HG kits to stick onto this, you can use a polycap to fit in the neck and attach a Gundam head and pop those shoulders out and replace them with big blocky gundam arms. And it looks really funny.
I can vouch for the "HG Dagger L" fitting fairly well. You can stick the legs directly onto the thighs (though they'll be a bit long). You do need to fit the unused polycap for that kit to sit properly in the neck joint, but the Dagger comes with its own neck joint, so it's a spare part.
It also works to some degree with the HG Windam, but you'll have to experiment with kits to see which ones are compatible.
30 Minute Sisters are Bandai's answer to Kotobukiya's "Frame Arms Girls" which are modular plastic model kit dolls with swappable equipment and parts.
They are meant to be interchangable with some 30 Minute Missions kits, so you can swap heads, arms/legs and other parts. I can confirm that you can put on a Portanova's head/arms/legs.
This kit contains:
The main torso (the upper torso is articulated and bends forwards/backwards)
A purple collar that is not attached (loss risk)
A set of purple discs for said shoulders and thighs acting as middle parts
A set of purple discs with 3mm pegs for the same, as well as wrists (arms/wrists/hands not included)
Two soles for the bottom of Rishetta's feet (feet not included, nor legs below the thigh)
A backpack adapter (there are two 3mm holes in the back, one at the top for backpacks and one near the bottom for tails and the like)
A neck adapter for using a 30MS head with a 30MM kit.
It's a little pervy, but funny. Unless you specifically want the big breasts for comedic effect, it'd probably be smarter to get one of the actual girl kits and you can do the same sort of kitbashing.
The only other difference is that "Rishetta" comes with orange accents/discs and soles, so it's a color swap.
Something worth considering is that some parts might be compatible with Bandi's "Girl Gun Lady" kits, or other Bandai "girl kits" (like Fumina), but I can't vouch for this.