No word yet on my 4.1 engine trouble, but I am still thinking about the 4.9 block swap. One thing I have picked up is that the torque converter on the 4T60 will need some beefing to handle the 50% increase in engine output. I am wondering if anybody knows if the 4T60-E torque converter would be a direct swap? The -E was used on the 4.9 so it should be robust enough.
Both transmissions use the same part numbers for their torque converters according to where I buy my transmission parts. http://www.bulkpart.com/Merchant2/me...=4T60-440-T4tc
As long as the pilot, bolt circle, number of splines and number of mounting lugs are the same, it should work. If I were doing the conversion, I probably would stick with the VCC type clutch. They are very robust as long as you're not towing. They don't work good with towing applications because the VCC introduces some slip and this extra slip while towing could generate too much heat.
My prediction from experience is that if anything fails on your transmission, it won't be the torque converter but it'll be the clutches or sprag gear.