AGG or ADY engine into 1.5 auto

I've noticed that 2.0 8V engines from the Mk3 Golf and others of the era seem to be quite popular and easily available, however is this a possible/easy conversion? 16V engine is too much, and I don't want to get into replacing the manifold, carb, etc. Can I transfer the following with no real issues:

carb inlet manifold
dizzy - do I need an adapter ring?
exhaust manifold etc - if not are new sysytems quite cheap?
torque converter drive plate etc?
right engine mount
coolant sensors etc

I realise I might have to rejet the carb - its a Weber conversion at the moment.

you would need to fit a 1.8 mk1/2 head to it preferably gti, as the inlet manifold ports are totally different. plus a tsr adaptor ring to fit either your old dizzy, or my recommendation would be mk1/2 1.8 kjet gti dizzy. good excuse to upgrade to electronic ignition if yours is points currently.

1.5 system will fit, but i would get a standard mk1/rocco/cabrio 4-2-1 gti system with the 6 bolt flange connection on manifold, it flows much better than the stock one, and plenty well enough for a 2.0 8v lump. Aftermarket will cost you but you wont notice much difference power wise unless the engine is heavily modified

all the old auto parts will swap, but i would worry that the torque converter wont deal with the power so try to find 1.8 mk1/2/3 auto torque converter then bolt your box on (or fit mk1/2/3 18 one, maybe ratios be better match?) everything else will be as per mk1 as you'll keep the carb, cables and such.

mounts will all swap, you'll just have to trim the mk3 timing belt cover to clear the driver side mount. use the mk3 rocker cover if possible, if it fowls the carby airbox then you need this timing belt inner trim piece to seal the hole when mk1 rocker cover is used: 048 109 173 d

coolant sensors you may need to swap to mk2/3 golf front flange and thermoswitches, depending where the 1.5 switches are as the 1.5 flange wont fit the mk1/2 1.8 head iof they're in there. If it was me, I would keep all mk3 coolant hoses and fit a new mk3 front flange if need be with 2 holes then fit mk2 carb thermoswitches in there. If the mk1 side flange has the coolant temp sensor in it reuse, if not use a mk2/3 1.8 aircon side flange with a later mk2 coolant temp sensor for dash (its 2 pin, 2nd pin just needs to be earthed) then splice all the relevant plugs if need be. finally swap the lower thermostat flange for mk1/2 as the mk3 one is no good for mk1/2 rad. the old 1.5 one will be alloy and straight fit

on the subject of coolign fit a 1.8 8v gti radiator and hoses, the 1.5 rad will be a bit small for my liking. cap the thin hose outlet on it with a short length of hose and a bolt if need be. mk3 thin hose takeoff is on front coolant flange see, id use this as neater,. If you dont have a header tank and dont want one, use an early s1 mk1 1.6 gti rad its bigger but with topfill cap on it.

finally, you need an electric fuel pump. an easy one if you can find is the later mk1 cabrio and scirocco lifter pump, it'll drop in and work with your odl fuel lines and is fine for a carby.  You'll just need the plug and splice power to it, I would recommend you use a kjet fuel relay to power it safely. How you do this depends on fusebox if its early ceramic or later blade

Great, thanks. I thought the inlet manifold ports wouldn't quite match up, and I forgot about the mechanical fuel pump. I'll have to price up the availability of the other bits and bobs and see if its worthwhile to do.