What kind of modifications can a Honda CG have?

So I'm planning on buying a Honda CG 125cc or the Yamaha/Kawasaki equivilant and I was hoping to make some modifications before the end of september, as you may know, the standard 125cc is quite small and light so I'm wondering how much it can handle. I'm hoping to do the following:

-Replace the engine with a 250cc or larger one
-Replace the front headlight
-Replace the body kit and frame to make it look fuller
-Put the front wheel-shaft thing down at an angle so it kinda resembles a harley
-Replace the HandleBars

and most importantly:
-Replace the wheels with fatter, better looking ones.

I'm planning to make 1-2 modifications per week at a budget of £200/week, how possible would you say my dreams are to make into reality?

I'd really appreciate answers and advice from someone who has done this before or perhaps does this for a living?

WHY?
For all the money to mod it to something that it was never meant to be you could have saved that to buy a bigger bike. Like paying someone else to throw your money into a welling-well.

Might take more money and a chopsaw and welder. Engine replacement for double size? Find a big single cylinder to put in small frame and you'll likely need motormounts changed, frame cuts. IF the larger engine is in same engine 'family' from the maker, then swapping relatively easy- the Honda 175, 200, 250 cc twin family for instance or the old 125, 150, 160 twin family with same motormount location, same basic cylinder height and inclined angle. Headlight is not a main problem, body kits mean some bracketing and clamping, not a big problem. Front wheel shaft thingy to resemble a Harley? That is a problem trying to figure out what you mean so Please CLARIFY. Handlebars replace- check length of cables for new bars attachment- if you want high bars might need newer. Longer cables and wire loom. Fatter wheels? How much fatter- the limiting factor is space between forks and swingarm, fender/frame clearance- might get a inch wider tire of same diameter, might need to go smaller diameter wheel for wide rims. CM400 has 4.50x16 wheel and can be swapped with 3.75 x18of CB similar model but gives the 'Fat' tire image. Most of your minor swaps have been done at various times, the wheels are what can be fitted and their are likely some fancy replacements that can be bought for the image and wouldn't be too bad handling-- might even be some kind of front 'wheel shaft thingy' on market. Engine swap for 250 is not likely going to be easy- might find a 150cc in same 'family' with same case, slightly bigger bore- the American market has a 150cc 'break' between legal 'light' not allowed on main highways and the over 150 cc engiens that can go on the interstate system while UK and European market has a 125cc break in class for most markets/drivers license use/insurance, etc. The main Japanese makers have models with basic same engine and frame for both markets- the American market will get the 149cc engine while the European market may get a smaller bore 123cc version of the engine or the Asian Market will have smaller and larger engines - bore size difference of couple mm on same stroke. This is more likely most practical engine swap-- but likely will be slightly illegal in UK or costly inspection and tax increase for you to be legal. Seems a lot of UK people trying to get sneaky with 50cc and 125cc class projects- drivers license is restricted to the smaller engine size models and big bore kits, engine swaps into small frame contemplated to dodge the law for a year or 2. Most of these projects are higher cost, risky legally and not worth the hassles. How about this? Keep it basically stock and legal, change the oil at 1000 miles/1600 kilometers and use the money to ride a extra 1000 miles a month, learn to survive in traffic for a year, then next year or 2 when you're legal to ride bigger cycle think about getting the 250 to 400cc engine with the 33 hp legal limit for your license. Your post leads me to believe you are a recent licensed rider with the graduated license restrictions yet. How long have you had your motorcycle license? Your age?