If the other bosch one wont fits, I wouldn't risk it.
Try these:
http://www.ebay.co.uk/sch/i.html?_nkw=c ... m270.l1313
As you say +ve is on rhs at the rear of the battey looking from the front of the car.Ie if looking at the terminals on the battery when it is out of the vehicle, the +ve will be on the left.
I have an optima red top, but they are 200 quid. they have 800 cranking amps fo fire car up in a flick of the starter
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'99 Z28 A4, 253 LS2 heads, 228R TSP cam, Patriol Dual Springs, Double roller timing chain, LS6 ported oil pump, OBX LTs, 3" True Duals, LS6 intake, 42lb/hr injectors, SLP lid + bellow, EFIlive COS 3 Speed Denisty Tune (self tuned), 3200 Circle D stall, CAI mod, KYB AGXs, Eibach Pro Front Springs, UMI panhard, LCA + Brackets, Strut Brace, Custom Subframe connectors, WS6 axle with 3.42s, 18" American Racing Rebels, US mirrors, 93 tail lights, 3.5 inch custom cowl hood. Mickey T's Street DRs on Vette-ZR1 wheels for the strip !
Best ET: 12.0 @ 116 mph (on a 0-60ft of 1.8 s)