I scrub everything with a biodegradable degreaser, a purple one with the unimaginative name of Super Clean which I get from the local big-box home improvement store. Some of these degreasers can etch bare aluminum, but this one seems pretty safe. Twenty nine years of chain grunge doesn't come off without a fight but perseverance will win the day. The forks will be removed for steering head bearing service, so that area will be detailed in its own good time.
This may be the nastiest chore in refurbishing the VFRs, but there's a certain satisfaction in the results. There's much work ahead, but no one likes to wrench on a dirty machine.