Several options and ways to go, depending on how much $$ want to spend, how close want to stay original in look and style, plastic / aluminum rads thru most parts stores are cheaper but then to me, so is the look.
I converted my '71 4x4 from 3 row original brass/copper to original HD brass/copper 4 row years back and never regretted the expense. Was not really costly at time but could be a bit more now.
Since your a paid subscribing member watch the For Sale ads, 4 row rads do show up from time to time in various states of use. A re-core is not cheap but I did that for my '71 Chevelle when had the 4 row brass / copper re-cored. If go to a 4 row watch for upper and lower rad brackets to show up in the parts section. New rubber cushions are available as are re-production 4 row brackets. Choices, choices, choices to be made.
Be sure you do a good fan clutch and metal fan. Don't go the flex fan route. Also a good fan shroud is a must for proper cooling. Just some thoughts and my $0.2 Good luck on your decision.
