Nice set up, what color insert are you using in the shifter? I have the same set up on my Mondia, Athena RD, Regina Syncro 90S 7 speed freewheel, Blue 7 speed insert in shifter, SRAM PC870 chain.
I tried both, regular housing and compressionless, the later shifting much better. You have to over shift just a bit, but it works really well.

This is when I first tried a shimano Freewheel, and a few different inserts in the shifter. Silly me, all the answers were in my Southerlands Sixth Edition. Green insert for Shimano , blue for Regina Syncro.