The correct answer is "No you can't"
The reason is that there are different line I.D.'s depending on IP and injectors to get the right "pop off" conditions.
Now having said all that, when I put 6.5 heads on my truck after I found a crack between valve seats a few years ago, I didn't have 6.5 lines lying around, so I carefully bent my 6.2 lines and fitted them up.
The engine runs fine.
BTW can you do us a favour and name the eBay seller so no one else gets a bad experience....
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)