The general reason told was that the 1400 was punched out and left less material to dissipate heat and increased dramatically the unsettling of the sleeves and therefore movement , warpage , frustrations.
Less troubles with the 1100 and 1300 but still open to the same issues.
Managing one of these going forward will be a challenge but a few guys like myself out there will raise your flag forever if you succeed. Just to see and hear it running like the old sewing machine sound they made.
Splitting cases , taking this serious , it’s enjoyable to witness being an almost 59 year old who started his Subaru life around 12 - 13 when my brother said “you grab that side , pull forward and then lift”. We had 1100’s , 1300’s and then onward often on his workbench.
Certainly brings back memories.
If my storage weren’t a bit overwhelming at the entrance right now , and dead of winter , I’d snag whatever I can for you. But I think you’re already fairly buffed out for what you’re doing LESS the shims. But those will show up or can also be turned out for you easily. Maybe even a better material.
Winter sucks but reach out to me if you need something and I’ll do my best.