Joined: Jan 2010
Posts: 9,797
Likes: 1,761
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
Is the OP aware of how the hi-limit screw functions, and of cable tension adjustment?
These are the usual approaches to lazy shifting toward the small end of the freewheel. The chain gap is expected to vary with chainring choice, but the rear derailer should be able to shift using either ring, especially the large ring.
Changes in chain length or axle position should take into consideration the chain's tension at all combinations of sprockets.