Lets say that you were going to sell these at auction. Would you crack them out? Send them to PCGS or NGC? ACG was not thought of very highly in the past. Not that many around anymore. Any value in the old holders?
If they are proofs, they are going to be proofs in the new holders as well. It's not as if they over or under graded a business strike. IDK if a point more or less will make a difference, and since you can't get these holders anymore that might have some appeal. 63 seems about right for the middle one. The bottom could go higher. The extra expense might lower your bottom line.
If you wish to sell them easily, definitely ! Quite the opposite in my opinion. I wouldn't be surprised if the mere mention of those holders dropped the value by half, maybe more. And I suspect it would drop the liquidity to almost nil for some folks. Of course an educated buyer would simply ignore the slabs and buy the coins - or not.
I pretty well agree with Doug, here. The old ACG holders are a big turnoff for a lot of people, but if you're buying the coin and not the holder then I shouldn't see why. You will have a lot better success selling (and higher return) with these in a PCGS or NGC holder.
Only you know what you paid for these. The calculation is YOUR COST + SLAB FEE versus what the coin ends up being worth. Why you would eagerly give over one hundred dollars of your gain to a TPG is beyond me. I may eventually buy a slabbed coin but I will NEVER send one in to be slabbed. You can easily sell any coin by deducting the slab fee from the sales price. You remove the waiting period and the disappointment of it coming back less than you expect. You sell AS IS WHERE IS and all the risk goes on the buyer. He is the one who gains or loses on the deal. He will lose many more times than he wins if you know how to properly grade your coins. You can offer to refund IF AND ONLY IF the coin comes back counterfeit. That makes you the good guy.
Submitting those proof Indian cents to NGC/PCGS would be a smart thing to do. He’s not going to waste money, instead he ensures they can be sold in no time and for a fair price.
Why not figure out how much you would be happy for, add the slabbing, and first advertise them here for a little less in the original slabs. It would only delay things for a week, and many on the forum likes holder history. They are attractive and original IMO, Jim
I think since you bought them and appreciate the old holders, then another experienced collector will do the same. Seasoned collectors will buy the coin and not the holder.