laza, do yourself a favour & do the conversion first, using the stock motor & get everything working properly up front. You won't believe how well they drive in an old Holden, especially a ute, you will have trouble keeping traction.

If you want more power later & you want to tow with it, be very conservative with your choice of camshaft. Remember the bigger the cam, the less low down torque you get, regardless of what other mods you've done. Also with petrol getting more expensive, remember the bigger the cam, the more petrol you will use, low down in the rev range. An LPG injection system is another option, but again do that later.

Dr Terry