Not too many "specialists" that do them on a regular basis as the MR2 is not that common.
G-Force Race Solutions in Vic
Wtf Auto in Perth
Advanced in Sydney
Ats Racing in USA
Many spread out...
Most parts come from overseas, and can save a lot of time and money organising most of it yourself. Some owners will ship in a built short block from overseas, some build themselves / in partnership with a shop, others just hand over cash.
Adding HP has many paths depending end goals of 3sgte / 5sgte 2.2, 2gr, kswap. Most of the time rebuilding / forging a 3sgte in cost vs outcome not the best path, however many factors if just refreshing.
GForce is said to be good, however can take a long while has been a comment.