RE: 70A carb changes??
The O.S. Max 1.40 RX doesn't use a "spraybar", but any changes to fuel metering would be in the mixture control valve:
OSMG6724 29481600 MIX CONTROL VLV #70A $19.99
The engine came out in 1996, and anything made after mid-1997 would have had the newer mixture control valve.