We did check with PSI and they said that they no longer have any of those and they referred us to Tennant.
Tennant only offers us the option of short block and a head.
We also checked a bunch of websites that claim to offer complete 1.6 Vortec engines, but all those claims turned out to be false. They are just too indifferent to take down their web ads.
We are currently straddling the fence on going that route or doing a complete evaluation of our current engine and head.
The tempting rumor of being able to get rid of the 1.6 Vortec for a (presumably) better brand of engine has caused us to pause while we try to confirm if there actually is a retro kit or if someone has been smoking something.