If your going for the high heat GBR tank why not centre it all around them?
Make sure you source wild or F1 Rams though - then as people are saying high temperatures - at last 28c and a low ph of 6.8 (which yours is so perfect!!) or less. The "classic" tank mates in this situation are Rummy Nose Tetras and Sterbai Cories.
If you want plecs in this situation looking around a few places suggest any plec from the Xingu river will work as it is naturally quite warm. L333 and L134 are also quite popular in warm water tanks as well.
If you did this route you could do something like
4 Wild Blue Rams
20 Rummy Nose Tetras
15 Sterbai Cories
4 L134
(or swap the Rummy and Sterbai numbers round which ever you prefer)
I think that less species in higher numbers is always a fantastic mix and creates a real spectacle
But your Endlers would not work in there as they are a more cool water neutral ph kind of fish.
Just to throw a curve ball - that you may be interested in... what about a micro fish tank but on a large scale. So pick out fish that have mini, micro and pygmy in the name

So if you go with the Endlers which would fit in the micro fish setting nicely but with the lower temperature range so maybe doing something like
6 Pygmy/ Sparkling Gourami
5 Endlers (though obviously the population can and will grow over time)
25 Galaxy Rasboras
25 Pygmy Corydoras
5 Dwarf Hara Catfish
3 Red Lizard Whiptails
Its a lot of fish but apart from the Red Lizards most of those fish wont reach over 1 inch most staying at around half an inch so the cluster of fish in the tank will be really impressive - especially in a well scaped planted tank. The Red Lizards are whiptail catfish and while they are a long fish they are also really slender and most of their size is more for balance and camouflage rather than a digestive tract producing waste. This tank will have a lot of activity in all levels as well
Wills