ITBs $2300 + block $2300 + head $1500 = $6100

JG will sell you a bare D series block resleeved and bored to 79 mm for $650. Just the block, no other parts.

Typical i/h/e GSR motor puts down 155 whp.

ECUs generally come with swaps.

The crossmember the part of the body/frame the front motor mount bolts to. The stock one doesn't leave a lot of clearance for the B-series headers, aftermarket ones are stronger and thinner.