Hi Marnuc,
Thanks for the kind words. The suzuki 125 is not vintage, its 2 years old. Bought it repossessed from a bank. The model is a Suzuki MOLA Its used by couriers and pizza delivery guys here in the philippines. I was new to motorcycles last year and decided to buy a small bike to see if I can modify it to a cafe racer. Once I gained some confidence, I bought the rusted Yamaha srv 250. Here's what I did to the suzuki:
Change tank to a honda clubman 250 (ebay) paint, pinstiripes and vitage BSA sticker
Change handle bars to drag bars and ebay mirrors
Change exhaust to peashooter style (ebay)
Change front to disc breaks (not necessary)
Changed the angle of the rear frame for the seat to be level
Make a fiberglass seat mold and upholster
The yamaha srv was even easier. Just changed the bars, mirrors and exhaust (all ebay), New avon tires
I cut an old gas tank in half and mounted it to the rear of the bike frame and cut the plastic seat pan and reshaped the seat foam then reupholster. Powder coated all rims and new paint job with stripe stickers prior to clear coat.
The EN 125 you chose can be done. The tank looks good already. Exhaust looks good too except for the small silver heat shield. You probably need to modify the rear seat frame to make it more "level" since it looks a bit high in the back. Not difficult at all. The choice of seat style is of course up to you. Personally, I would change the bars and mirrors remove the side indicators and put a pair of rubber boots on the front fork to make it a bit more substantial. Spoke wheels are a nice vintage touch as well. Good luck on your build and feel free to ask questions. Cheers (don't forget to post it when you're done)
Here are some pics of the MOLA before the build and the inspiration bike I saw in another website.