The old Check valve- replace or chuck it

I was asking questions a month about about EDR on this job. This 8 Unit job is finally happening, end of this week or the beginning of next.

This is a one-pipe job, pretty normal

The current boiler: It's a Goliath. No header, equalizer, Hartford. Looks like 1980's. Sadly, the LL told me he got a quote that from the same 'well known' boiler installer that installed this one, (Company out of the in Springfield area), and they were going to install a new boiler (same size), connecting to existing piping (like, still no header, equalizer, Hartford). Same BTU, re-use the same giant 601 series gas Burner (700,000 to 1,500,000 Btuh)

I'm installing a Peerless EC05

Anyway—theres a 2" wet return with a check. I am tempted to yank it. I suppose with no equalizer, a check is needed. With normal piping, it isn't. Do you agree? (Checks may me scared😒)

Secondly, are there risks ramming a hose up the return to wash out some mud? I don't want to inadvertently push a pile of mud up and make a possible small problem a big problem. I can fit a kiddie pool in there, the boiler room is a little lower than the rest of the basement.

Thnaks