Rubbish spec for the power.
A cossie with std head/cams/pistons/rods will easily make/take this power, with a T34.48, running around 24psi, all day long, don't need double springs with std cams.
I would use a YB 0611 HG, will handle this easy, block will need boring not honing but machine shop will do this for you, hopefully with a deck plate attached, as plastiscine is more riggid than a pinto block!!
Will be a waste of money for porting etc, head will likely need a rebuild if much over 40,000 anyway, and not always cheap.
The standard compression is fine, nowhere needing to be lowered with consequent loss of low down power, off boost power, same with the cams, the exhaust one is certainly ok, the inlet can be changed to BD15, this will give a more agressive punch as it hits the boost proper, but will likely lose out to a std cam before this.
A T34.48 will do this power all day long, you could go .55 or .63 but this will just make it lag city, the reason why at the same power they feel more punchy is they have more low down loss to make up for over the .48 which spools that much quicker, depends what you want.
Heads have been used much less than that, can't long stud 205 block, and not needed, I would use ARP personally, if fitted correctly they will not cause block cracking/lifting, but do need measuring, but could also use the std ford stretchy bolts.
Use Cometic inlet gaskets as re-useable so save again and again on money.
Forget T4, as pretty useless as everyday car, unless you like TYPE R's and constant gear changes due to no bottom end!!
L6 mapped will do the job no problem, not everyones choice, but if stopping at a certain point with mods would be cheapest, do all mods get it mapped once and leave it, if you intend further on more mods, you may want to carefully look at costs of keeping the L6 versus a aftermarket ecu, a bit more freindly to the home/end user as regards mods.
tabetha