Are you needed to start out with gas becuase glow fuel is not available or is it cost restraints. well I'm not sure what kind of stores you have in pakistan but here any department store or home and garden store would have a weed whacker, or a chain saw or gas powered blower or any other hand held gas powered equipment with a 2-stroke engine.

take this kit[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDJB9&P=0]goldberge trainer[/link]

copy and add at least 30% to the size or every part, need a good bit of balsa and lite plywood.

then modify a gas engine so resemble these specs, or buy this

[link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=ZENE26AEI]gas rc engine[/link]
these were designed for rc