I get that you don't want to hear what I said, but your ability as a welder is not the issue. It's the ability to work out what forces are involved and how to tame those forces. There are all sorts of abominations on this forum and others and few of them are ridden anywhere by anyone. And just because you have seen someone else do it doesn't make it safe or smart.
I have known a lot of people who do drugs and some of them sare still alive and not in jail, but that doesn't mean I should follow their example.
Let's just start with one example. Look at your swingarm and imagine the forces acting on the rear wheel. When it hits a bump it wants to move upwards. What resists it are two shocks mounted close to teh wheel, so that all teh forces act locally and there is little force causing the swingarm to bend.
Now imagine the rear wheel trying to rise in your configuration. What resist it is a shock mounted let's say 1/3 of the way back from the pivot, so now the swingarm is trying to pivot around a semi rigid mount (the shock) and it will try to bend there. Bracing might help a little but the skinny little swingarm tubes are basically too small to resist bending that way and will bend and fail.
You could replace the swingarm with one that's twice the depth with a decent bridge like one from a modern bike of course.
Next there's shock geometry to consider. How far will the wheel move and over the range of movement, how much will the shock be compressed in that movement? Let's say the wheel moves 120mm and the bottom mount moves say 40mm , is the rate of movement the same over the first 20mm of movement as the last 20mm. If not, is the rate rising or falling?
Based on that range of movement, what force is applied at the rear wheel say as it hits a bump or over a long undulation around a corner when it's also loaded up with centrifugal force? That will give you a starting point to calculate spring rates and damping rates.
For a cafe racer that will never get much past Starbucks or bike night, some of those calculations can be less than 110% accurate and still be OK, but this stuff all matters if you want to build a motorcycle. A bike is not a piece of art that is designed to only be ridden at photo shoots to show off a fab shop so they can sell T shirts or simpler work.
A motorcycle is an engineered product designed to work in a harsh dynamic environment where failure can result in severe pain or death.
Please check the attitude at the door, and engage brain before operating keyboard. We are not here to bust your chops or to blow smoke up your kilt. People are trying to be helpful.
There are a couple on well thought out 360 and 400 builds on here. Juniors Tin shock 400 is arguably the sharpest and embodies the Cafe Racer ethos.
