thanks guys i will let mechanic know what advice i've recieved.

must put things straight expected hp is 350 not the 450 i origonally stated
but once heads have been ported mechanic will properly profile motor and then we will be sure where we're at, the 450hp was from a 308 stroker profile he showed me not my motor, i got mixed up.

Thats better, 350hp or 260kw (180-200rwkw) is easily achievable with your mods. I would still try and convince your mechanic to look into other cams like the Crane 2031/2030, IMO they will give better useable power and drivability compared with the E303 design.

motor has 2031 already but he's fixing up motor from the guy who ripped me off spent $6500.00 and all he did was 2031 cam race series flatops,balanced motor and ported the old e7 heads without useing flow bench,new mechanic recons parts $2000 tops,but he is at least profiling on paper first to show hp and then give accurate quote.the guy who first built used standard pushrods and standard rollers 1.55 i think,cam won't work properly

Yeah the 2031 really needs 1.7 rockers, not the stock 1.6's to work properly. With the 1.6 rockers he should have used the 2030 cam which is basically the same as the 2031 (a bit more agressive) and uses the 1.6 rockers. You can still often use the stock pushrods though, depending on alignment and preload. The 2031 cam is an extremely good match for GT40P heads, you should get a good result. Personally I wouldn't have bothered doing the extra porting but it will give you a slightly better result. Before the supercharger I had a very similar engine to yours, Ported GT40P heads, Ported Cobra intake, balanced and blueprinted bottom end, crow cam with 1.72 rockers etc and it did give decent power (around 240-260kw). Dont know what you have already but you will probably need a better fuel system with 24lb injectors, 70-75mm MAF and maybe larger fuel pump.

i think were we're going to use 76mm throttle body ,i've already installed a maf of a gt not sure the size but its alot larger than the standard as with injectors i was told by a couple of specialist not to worry unless i install a blower as improving the computer will give extra fuel.

76mm TB is way too big for an NA EFI 5L, you will end up loosing too much throttle response. Even 70mm is a bit big but the max I would ever go to. The stock 19lb injectors can be pushed to around 180rwkw (230-240fwkw) but that means upping the fuel pressure quite a bit which will reduce the life of the injectors as well as cause idle problems. Under normal driving, computer mods alone will not supply more fuel as it is controlled by the MAF to maintain correct AF ratios. Full throttle runs need computer mods or higher fuel pressure to stop from leaning out, but with that sort of power you will need to do both. Pussing the injectors so hard will also affect reliability because with high fp the injectors aren't as accurate and if anything goes wrong it will quickly lean out costing you a head gasket or worse. IMO the proper way to go about it is to run some 24lb injectors and a matching Pro-M MAF, that way you don't have to do any computer mods and there will be plenty of fuel at stock fuel pressures. All up it will cost a around $1000 but worth it for the reliability.