A few thoughts for ya...
1. Is there a reason why you are using a combination of DME and LME, other than that you have both hanging around on the shelf? I would suggest that, if you are buying your extract for each batch rather than using some you may have hanging around, you could use 6Lb DME or
7Lb LME just to simplify things.
2. The reason Victory and some other malts must be mashed is because the starches in the grain are too complex to be fermented, so they must be broken down by enzymes into fermentable sugars (mashed). If you are planning on steeping your grains in a bag in your kettle, you could keep the Victory malt in, drop a pound of extract, and mini-mash your grains with 1.5Lb of 2-row base malt (or something English like Maris Otter) at 152˚-154˚ for 45 minutes or so. Although, I don't know that the character of Victory malts something that is make-or-break for an English (or American) IPA. It might be more "true to style" without it.
3. London Ale III yeast is a lower attenuating strain meaning that it ferments a relatively lesser percentage of sugars in the wort. This will make your brew end up relatively sweeter and fuller bodied. If that's what you're after, go for it. If not (and most English-style IPA's I've tasted are not), try a yeast with a higher attenuation percentage like 1098 British Ale or 1335 British Ale II.
PS - IPA is style of English origin. What makes an IPA English-style is English ingredients and an emphasis toward early hop additions (60+ minutes). American IPA's typically use American ingredients and, although well bittered early on, have more emphasis on hop flavor and aroma from later additions.