Was thinking about this as well. Noticeably cheaper than the 200r4 as well. But I believe the 200r4 requires little to no modification since it’s very similar to the th350
I'll agree the t200-4r shares very little with the t350, it does bolt to the motor without any adapter, uses a turbo 350 drive shaft, uses a standard speedo cable, can use the TV cable much like the kickdown cable with only the need to slide the cross member back to the turbo400 position with a commonly available trans mount. That's a pretty simple install with little to no modification to me.
I was thinking more along the lines of durability. In stock form, I think the 350 can take more abuse than a 200/2004R. It takes less to beef up a 350 than the 200.
No argument there but for a cheap and easy beefed up 200-4R, they are hard to beat for easy of conversion.