Any way could measure out thick your 4 row is?
I have exact same setup with stock radiator.
Curious if 4 row would clear, what brand radiator?
Measuring from the edge of the core support to the outside edge of the top tank, I read 3 5/8. I got it from here, model 036040 AAD
http://www.usradiator.com/radiators/plymouth.html?cat=1661The one at the bottom of the page, 26" small block. Factory shroud bolted right up. I use the tranny cooler in rad then out to aux cooler.
One caveat though, I had leak in top tank to core seam during warranty period and a mounting strap separate from the top tank. rather than send it back to CA, I was able to take it to local rad shop to fix and promptly reimbursed by US Radiator
I think the failure was due to body flex in that area as opposed to product failure. Overall, I'm happy with the radiator, it looks mostly stock, no numbers on tank, and keeps the 340 with a 3000 stall converter cool even in S FL summer heat.