Which one? MSD AL6 or MSD AL6-2 for my stroker 418 (340)

Hi Guys..

Just wondering which system to go with? is there a difference other than the Built-in 2-Step Rev Control lol!! I can get the AL6-2 a little cheaper be it only $5 difference but both on the shelf here in the UK and the Duster is a little tuned???
Sick of larking about with the crappy stock ignition, fitted a MSD Blaster 3 after running a Blaster 2 for 1000 miles but its back firing now and think its due to the stock Ballast restricting voltage? not sure why it does not effect the Blaster 2.. in fact went to refit the Blaster 2 today but the negative post connection is cracked so not happening.

Only really interested in these systems as we are very limited on whats available here in England.

it was a ex drag car in Orlando but now a road car and never see's the track, but only used on sunny days so not that often...
The engine was a 1971 340 block, now bored 40 over to 4.080,
Scat 9000 series 4" cast crankshaft,
ARP main bolts,
Scat H beam forged rods with ARP studs,
Icon (Keith Black) 744 forged flat top pistons with valve reliefs,
Hastings racing moly/ductile rings,
Clevite H racing rod bearings,
Clevite full groove main bearings,
Clevite cam bearings, rotating assembly fully balanced (Pistons, rods, crank, balancer, bearings, pins and flex plate)
Elgin high volume oil pump,
Hardened oil pump driveshaft,
Modified Moroso deep pan sump and high flow pickup.
Comp Cams XE274H cam. (242 duration @.50.492 lift)
Original 71 J heads 2.02 inlet valve, 1.60 exh, fully ported,
Exhaust valves, re seated,
Comp cams positive lock stem seals,
Mopar performance double valve springs,
Tungsten retainers 4 groove,
ARP head bolts,
Felpro 521 SD high performance head gaskets,
10.75:1 compression ratio,
Factory rocker arms and shafts, lifters and hardened pushrods,
Edelbrock Victor 340 single plane high rise drag inlet,
Holley 750 vs elec choke, 14"x 4"
Moroso carb spacer,
14” K&N air filter,
Mopar Performance cast ali valve covers,
High flow water pump,
160f thermostat,
Elec dist converted with modded weights and springs for advance curve,
MSD Blaster 3 coil,
ACCEL 300+ 8.8mm Ferro-Spiral Race wire set,
Holley blue high flow electric fuel pump with Holley regulator, (110 Gallons per hour)