I did not click the links Matt posted but I would run your passenger side under the SBC oil pan (assuming engine placement will allow) and link both sides with y-pipe then route out the rear with 2.5"
Speski OffRoad LTD, Cargo Solutions for Toyota 4x4's http://www.SpeskiOffRoad.com
"80 series, with a fridge"
1976 FJ40, Project with little progress.
2004 Starcraft 10RT