318 crank into 340? pitfalls

:drama::drama:keep in mind what I,m trying to do.build a 325-350 H.P. 340 that will run on (89) pump gas.bolted up in front of a 4-speed tranny.$2,000.00-$2500.00 budget.I have the 340 block that has been squared and decked-will bore to 0.40-$200 - ,pistons come out of top .020,thinking that new pistons may need to be milled -turned to lower cr.$80- have a set of 587-j heads that have 2.02 valves, ported ,polished will need to be fresh,nd up and surficed-$350 turn crank-$120,true up my already lightened rods-$80 cam bearings and freeze plugs install $50,balance-$,300 vat and mag heads and block-$100,press new pistons-$80.that puts me at $1360.00 at the machine shop.thats if my valves are all good.then we move on to parts,pistons-speedpro L2316f40-$313,rings $60,bearings & freeze plug set $160, felpro bebuild gaskets-$100,valve springs $50,timing chain cover and water pump $100,considering reusing my timing chain and high val. oil pump?cam and lifters $300 ? I haven't really started checking prices very close because not sure what I need in this area.misc $150 paint,trowout bearing,filters,ect.ect. that puts me at about $1150.00 in parts.$2500.00 or I could sell all this stuff I have and buy a engine already built.any idea what the parts I have might bring??? I see some really high prices out there but I don't know what this stuff will actually sell for in a timely manor.whats you,re thoughts????