<blockquote><I>"i have tried with heating vent tape and that works fine but sometimes pellets stick to it"</I></blockquote>Have you tried real aluminum foil HVAC tape? It's actually soft aluminum with an adhesive on it and it sticks very well. D-I-Y centers like Lowe's carry it. I use it in powder bushings and if powder doesn't stick to it, lead certainly won't.
<blockquote><I>"Check the line of Hornady bushings to see if they are incrementally smaller or larger than the PWs."</I></blockquote>Hornady powder come in increments; the shot bushings are the same size as P-W's. The OP wants a smaller shot bushing.
I do not like tape to reduce a bushing. It is possible for some of the shot/powder to find a way behind the tape at the top of the bushing. The top of the bushing slides past the hopper many times and this can work a little flap of the tape over the bushing hole. This will result in a very light drop. It happened to me. I now use purple fingernail polish. I did not select the color, my wife did.
Aluminum foil HVAC tape is not your garden variety tape. I've never replaced a piece of HVAC foil tape because I had to. I've only replaced to fine-tune for a new batch of powder. And when I do, I have to use a pointed X'acto knife to get under the tape and pry it off the bushing. I have bushings that I use constantly that have had the same piece of aluminum foil tape in them for YEARS and 10s of thousands of drops and the tape is still in place and still tight.
If that isn't far enough "down the road", I'm not gonna live long enough to get there.
7/8 oz. is 24.8 grams. 1 wrap of aluminum tape inside a 7/8 oz bushing should do it. The problem with opening up a smaller bushing is that you can't put it back once you remove it, and steel bushings are a lot tougher to work with than aluminum powder bushings.
The OP didn't sat whether he was going to use these shells in sanctioned competition. In competitions 370.37 grains is 24 grams; 370.4 grains is illegal. The drop can be lighter than 24 but it can't be a tick over.