I'm not familiar with the Riv'* and how the engine bay is setup. But, I'm going to assume the forward part of the engine, (not the left bank, but the pulley part) has a mount that bolts to the passenger side of the engine bay. If you can remove this mount, it should give you enough space to shift the engine towards the passenger side. Again, you will need to support the engine and transmission somehow. A piece of 4x4 lumber running from strut tower to strut tower and some 1" ratchet straps should work to support both. 2 for the trans and 2 for the engine.
1997 Pontiac Bonneville SEi-SCRAPYARD
2000 Chevrolet Blazer LT 4X4 4.3L
2002 Chevrolet *-10 LS Ext Cab 4X4 5.7 V8