Short oil filter w/headers vs 90 Degree set up?
If you use a 90 degree adapter, the trick to getting them to seal is use a big copper washer between the bolt head and the adapter body. That dang fiber washer gives up over time and it starts to leak. The copper washers that I use are 3/4 ID x 1 1/8 OD. You will need to hone the ID just a tad to get it to fit the bolt.