@arifmian
doing a swap on ANY car requires you first change all the bushes, shocks, steering components etc for upgraded units, then you'll have to uprate your clutch, pressureplate, etc and get your gearbox strengthened somehow (i'm working on this at the moment).
next you'll have to uprate the gearbox mounts to stronger ones, replace all boots for your drivetrain, replace/upgrade all parts relating to your shifter and fit disc brakes (at least at the front) with a rebuilt or new master cylinder and upgraded brake hoses.
once you have done all the ground work, thenyou can think abotu swappign engines, this is why my 1303 only went from 1300 Dual port to 1600 dual port for now, and already i find that this engine can get me into alot of trouble since it can push the car to speeds that my brakes cannot handle.
as far as costs are concerened, the faster/more powerful you want to go the more it'll cost you.
a simple 1650/1776/1835cc upgrade to a 1600 dual port can range from £100-6000 pounds depending on if you swap out the heads, rockers, cams, valve springs, fan, shroud, ignition, coil, breathers, external oil cooler etc. and what carbs you go for.
let us know what you have in mind and we'll be able to guide you better. i'll be back online later today hopefully.
my car is on the road and has been for a while, i just am a stickler for details so i will never be happy with whatever i do to it i'm actually taking it out right now too.