The Scotland lock missed the autumn international series with a groin injury but will return to action at Scotstoun as one of seven changes.
Gilchrist is joined in the second row by Andrew Davidson, back after an ankle injury. Their inclusion sees Jamie Hodgson move to the bench, while Ben Toolis misses out with an ankle injury.
Edinburgh, who won the first leg 10-7, rotate their props with Rory Sutherland and Simon Berghan starting, and Pierre Schoeman and WP Nel dropping to the bench.
There are three changes in the backs, with wings Jack Blain and Eroni Sau coming in for Duhan van der Merwe and Darcy Graham. Van der Merwe has a knee injury while Graham misses out for personal reasons. The other change sees Nic Groom start in place of Henry Pyrgos scrum-half.