Well, ordered an M4E1 with SBA4 brace. Also ordered a complete side charging upper from Bear Creek Arsenal with 10.5” 1:7 in 5.56. Would have preferred a 12 or 12.5 length but times limit choices. May yet order a longer barrel to fit the upper but will certainly try this first.
FYI these folks:
https://modernwarriors.com/product/aero-precision-m4e1-complete-lower-sba4-psb-black/still list having 4 complete lowers like mine in stock for $355 plus shipping.
Optics. $200 range dot type tube or screen. Suggestions?