Soo.. onwards with the bike..
Based on you guys' post we had a good look at the situation regarding the drive.. the extra shaft on the crank and the play etc.
We have put the bearing more inwards and closer to the crank. Everything has been moved more inwards quite a bit.
We have checked there is enough clearance on the rollerbearing to take up any play.. and I don't think it will be an issue to be honest.
In the topic of savagebob he simply pressed a bearing in the cover.. and that also held up, so I think this should definately work. If not.. new cover and we start over

It is a bit of an experiment after all

Although it is very difficult to do any welding on the cover due to the material, welding has gone well.. everything has been centered and it all fits perfectly. No warping..
The extention shaft is made of hard steel. It has to be altered and shortened for the new dimension of the bearing and bushing etc..
Will have to be done by a machining expert.. so again have to wait for this.
For lubrication I am hoping there is enough splashing around so that the bearing will at least receive some. Savagebob had issues with oil leaking through his pressed in bearing so there should at least be some oil being thrown around in there.
Honestly, I don't even want to think about setting up a seperate oil system just for that bearing.
I did read through the enitre topic of DragBikeMike on the oil system. It is a shame it is so much work to do that type of upgrade..

I would feel more comfortable with an extra oil cooler on the bike. But maybe down the line... will think about it. It will also look nice to have something like that connected.. and should help the bike. Also with the way the exhaust is routed.
I am not aiming for any maximum power gains though.. although more than stock is definately expected.
Ow, and thanks everyone for your inputs!

Some more pictures:

Here the bearing used for welding is in, this will be replaced with a fresh one: