Kasei was making 1500 HP with water injection by 1945, the Kinsei did it in 1944 with 1900 HP? Something needs to plug the gap in 1943-44.
The altitude power can also be compared: 1350 HP at ~13500 ft ft for Kinsei 13, 14 and 15, vs. 1050 HP for the best Kasei of 40's series. Or, 1250 HP for Kinsei 13, 14, and 15 at 20000 ft. All figures are for 'military power' per US nomenclature, without water injection.
With water injection, Kinsei early 20's series was supposed to do ~1730 HP at 16800 ft, the Kasei 50's ~1240 HP at 18500.
Again, with w/i, The Kinsei 27 was good for 1700 HP at 20300 ft, while Kasei 60's series did 1490 HP at 16700.
Basically, the bigger Kinsei was making without water injection the same or better power than what Kasei did with water inejction. The take off and altitude power of Kinsei was much better.
Advantage of Kinsei vs. Homare will be earlier availability (and reliability) - aircraft powered by Kinsei were in use before 1942.