Prashant,
Perhaps you can do what you want with the 7824 / 7924 devices. There are some advantages, and also disadvantages to this approach. I expect you might need 8 to 10 of each P/N to supply your 5A reliably.
These devices may be paralleled using balancing resistors, but the result is poorer voltage regulation than you get with a single device. This may not matter at all in your application.
Can you tell us what sort of load this will be used to power?
And, do you know the DC input voltage the regulators will encounter over line and load variation?
Unless you get lucky, a transformer to provide the raw DC to the regulators will be by far the most expensive and most difficult to source item in your parts list. The design needs to start there.
A note on the 1.5A vs. 1.0A ratings. I'm sure there is variation among devices from different manufacturers, and even from the same mfg at different times. However, the parts were originally rated for 1.0A and later re-rated at the higher current value. The same identical product. So I would not count on one actually being more powerful than another.
Ted