OK so I've been planning what all I want to do to my .22 disco. Currently it has an hdd and three screw trigger mod. I don't currently have a curing and only other air rifle I had was a 392 I sold to upgrade to the disco which I have now had since like April or May.
Little advice if possible, please.

I want to add a BNM multi shot breech. Will the hdd still fit and work?
I would also like to ad a shroud or half shroud and use a barrel something like 4" shoter so the overall length of the gun stays about the same. Does anyone know how much this would affect the crosman barrels? Velocity? Energy? Precision/ accuracy?Or should I upgrade a a Lothar Walther? Is there a cheaper alternative to LW that would work?
Lastly I am thinking of swapping out the disco trigger pack for a prod trigger. I know at that point I will need to replace the stock, but has anyone had any issues with this?
Thanks!