Never seen these in Karachi but I know many who grow similar sized fruits in Florida USA... I'll try to get the seeds.. Karachi's weather is ideal for Papaya cultivation..
I'm growing some F1 variety from Aloha papaya seeds. Don't know if they'll be this big but should yield quality papaya inshallah. The seedling are good sized now and hopefully will flower around September so I can separate the hermaphrodites.