The ST703 tank fits either the C703 round or C704 elongated bowl.
MaP was 550 grams and worked fairly well.
The down side was splash onto the seat, it's a washdown bowl, not a siphon jet like the Dalton or Drake.
I had one for a while, and it worked well, however when it was replaced with an Ultramax, it was all over for the Reliant CST704.
The Dalton and Drake are better.