Daniel, from what I see the 650 and 601 are quite different wings the 601 has a three piece wing and the 650 is two piece wing, this spar is drilled  and riveted and is set at whatever degree the wings dihedral is on the 601. The pictures I've seen the airfoil is quite different as well. 

Hi Daniel,

we don´t use the seats but only the pro-fit-cushions in standard width. It consists of three parts for each seat (back, bottom, front thigh). Bottom and front thighs are avialable in three different thicknesses dependent on the pilots length. The thin cushions are well for me (190 cm), the thick cushions are well for shorter persons (175 cm). We have both and exchange it with the pilot. It fits extremely comfortable into the ZODIAC´s bended aluminum seat sheet is very lightweight and looks perfect. The cushions can be easiliy fixed with welcro strips.

For purchase look e.g. here: https://www.cobraseats-usa.com/item/pro-fit-cushions

Best Christian