No way of knowing exactly how much your #18 powder bushing is throwing without verifying, but Hodgdon's MEC bushing chart shows that at 18.7 grains:
https://hodgdonpowderco.com/wp-content/uploads/2023/09/mec.pdfBPI Advantages manual (page 269) has 1oz loads in Fiocchi hulls (also straight wall) with Longshot and a BPI PT2094 wad, and the 20 and 20.5 grain loads require an overshot card over 1 oz of shot. 22 grains of Longshot doesn't require an overshot card.
The book has the velocity listed as follows:
20 grain - 1275 fps at 10700 psi
20.5 grain - 1320 fps at 11400 psi
22 grain - 1340 fps at 10500 psi
Of note - BPI doesn't list the PT2094 anymore, so I called them about it a long while back, as I wanted to get some. They said their SG20L is what replaced the PT2094. It doesn't look like your 2094 Saber, so they aren't the same wad. The cushion section is significantly different. Your Sabre wad cushion is similar to a Helix Cushion Driver wad and has a 4 petal cup, while the SG20L is like a circle with dots on each side and has a 2 petal cup.
All the best,
Glenn