You can reuse your 2g coil stuff, but you'll have to figure out how to mount it. 1g coil pack and power transistor mounts different on the intake manifold. Only difference on a 90 motor that you need to be concerned with is the external oil cooler. The coil pack and power transistor are also 90 specific. A timing cover for a 90 fits all 6-bolt motors (ie 89-May92). You'll need the 1g thermo housing as the 2g mounts differently on the head. You also need the 1g waterpipe, etc.
http://www.magnusmotorsports.com/article_1g2g.htm
Read...it answers most of your questions.
Wiz