Boss + 90 bend

[crispy_wafer]

I'm looking to bring a waste out of a Boss and go vertically ASAP with the least amount of protrusion, so I can keep the 50mm inside a 97mm or so stud wall.  I'm looking to see what combination of components I need to achieve this...  I'm using floplast solvent weld for this,

 

1)  I've test fitted a bit of pipe into the bend so it sticks out a couple of mm then pushed the assembly into the boss and it fits quite snuggly and with a bit of SW  I reckon it would take, but I'm not sure if this is a correct way and I'm just storing up a problem for myself later on down the line. 

2) You can get boss plugs to SW pipe into the add a bend, but i'd then be bringing the bend out further than I'd like. 

3) And finally you can get a conversion bend that I guess would fit into the boss plug.  However screwfix dont have these in at 50mm.  Toolstation have some, but these are aquaflow brand, any thought if these are interchangeable?

 

What the best way to go about this.

 

[TonyT]

Use a street bend, or conversion bend?